The 2016 Disabled List - part 2 |
| 1B 2B 3B SS IF | LF CF RF OF UTL | LHS LHR RHS RHR C |
The following chart shows the number of Placements by position that were placed on the 2016 DL. The percentage is the portion of placement to the total on the DL (561). So therefore, RHS (Right Handed Starters) represented 25.8% of all the players placed on the DL in 2016.
The total percentage of pitchers on the DL was 56.0%.
Not surprisingly, all pitchers (Starters and Relievers) head the list of players placed on the DL in 2016. Pitchers represent 56% of players placed on the DL even though they only represent 48% of the MLB roster (assuming 12 pitchers on the roster). However, Left-handed relievers fall way down on the list at 3.9%. Some of this is explained by the lower number of left handed pitchers on the major league roster.
But how does this year compare to other years?
The next table represents all Placements on the DL from 2009-2015 (7 previous seasons):
We find that the percentages of Pitchers placed on the DL in 2016 are very similar but with a 3.8% increase compared to previous year’s averages (2009-2015).
We find that the percentages of Pitchers placed on the DL in 2016 are very similar but with a 3.8% increase compared to previous year’s averages (2009-2015).
In calculating the statistics on this, we find that the difference is not statistically significant with a p value = .53. So there is no significant change in the percentage of pitchers on the DL in 2016 compared to position players. Of course this does not mean that the number of DL pitchers has not increased. It has! This indicates that the new record of 561 players placed on the DL is not caused solely by an increase in injured pitchers but rather it due to increases in players of all positions.
DL Days by Position
Moving on to the amount of DL Days lost by position, we are going to first breakdown positions by DL Days lost similar to what we did with placements. We added a new metric that I call Severity Index Number (SIN). This is simply how long a player takes to recover from an injury once he is placed on the DL. In this case we will not be looking at specific diagnosis but rather how long it takes a pitcher or a player to recover from any injury. Eventually we will cover that but right now we will stay in the category of a player’s position.
This is a table of DL Days in 2016. This is similar to the table that we did with Placements.
As expected, the ranking of the positions is very similar to the placements. Now we will condense the pitcher’s numbers:
We see that percentage of DL Days at 63% is higher than the 56% that we show with Placements. Let’s see if this has changed from the data from the previous 7 seasons.
These tables indicate that there was no change in the percentage of DL Days lost to pitchers between the two cohorts (2016 vs Average of 2009-2015).
Severity Index
In working with DL data over the years, I saw some teams that had low DL placements that resulted in high DL days lost and some had the reverse; high DL placements but low DL Days lost. It seems that some teams had more “severe” injuries that required a longer healing and rehab time than other injuries. By using a simple calculation, this can be captured in one number that I call the Severity Index Number or SIN.
Severity Index Number = Total Number of DL Days/DL Placements
You can look not only at a particular team but the entire league over a period of time. This is demonstrated in the following table and chart, examining SIN from 1998-2015.
The chart indicates that the Severity Index Number is pretty stable with no increase or decrease over the past 18 seasons in spite of increases in the number of placements over the same period.
This trend line that has a p value = .64 and a R2 of .01 indicating the changes are not statistically significant.
So how does 2016 stack up against the previous 18 seasons on SIN? As you can see, there is only a small insignificant change from the previous 18-year average.
Two points that need be summarized here is that there has been no increase in the severity of injuries and the average of 55 days is below the 60-day DL requirements. The average player’s injury does not take over 60 days to recover and therefore does not necessitate transfer to the 60-Day DL.
Let’s examine the differences between the Severity Index between Pitchers versus Position Players. From the tables below, it is not surprising that Pitchers spend more time on the DL per injury than position players. Some of this may be due to the fact that it typically takes more time to rehab and conditioning a pitcher, especially a starting pitchers, than a position player. This is reflected in the fact that MLB allows a pitcher to have 30 days to rehab in minor league games as opposed to position players who only get 20 days.
Here is the table of all the teams in 2016. I usually do not like to list DL statistics by team because some people think a higher or lower number with some variables are a reflection on the quality of the medical team. In future blogs we will look at the multiple variables that go into players on the DL and the potential causes of injuries in baseball. But here is the 2016 by SI and Team:
This shows a large range in SIN of 31.6 to 89.1. The Standard Deviation is 14.4.
Conclusion
Unfortunately, the numbers related to DL has gone up compared to what was a record year in 2015. DL Placements (561) and DL Days (31,662) have eclipsed the short-lived record of 2015 as was shown in Part 1 of the analysis of the 2016 DL. In this portion of the analysis we looked specifically at injuries by positions. Although the total DL Placements rose, we did not see one position group reflect a significant change. It appears that the increase in injuries occurred over all position and not just pitchers as one might assume.
We also introduced a new injury metric, Severity Index Number (SIN). This number reflects how long a player remains on the DL and overall indicates the severity of the injury he incurred. Although the Severity Index has remained constant over the past 19 seasons, it does vary greatly from team to team. Not surprisingly, pitchers have a higher Severity Index compared to position players (63.7 days versus 47.2 days).
Conclusion
Unfortunately, the numbers related to DL has gone up compared to what was a record year in 2015. DL Placements (561) and DL Days (31,662) have eclipsed the short-lived record of 2015 as was shown in Part 1 of the analysis of the 2016 DL. In this portion of the analysis we looked specifically at injuries by positions. Although the total DL Placements rose, we did not see one position group reflect a significant change. It appears that the increase in injuries occurred over all position and not just pitchers as one might assume.
We also introduced a new injury metric, Severity Index Number (SIN). This number reflects how long a player remains on the DL and overall indicates the severity of the injury he incurred. Although the Severity Index has remained constant over the past 19 seasons, it does vary greatly from team to team. Not surprisingly, pitchers have a higher Severity Index compared to position players (63.7 days versus 47.2 days).
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The 2016 Disabled List - part 1
Stan Conte, PT, DPT, ATC
Stan Conte, PT, DPT, ATC
This is the cover of the infamous “RedBook” that was published for MLB Club Only in the late 1990’s and early 2000’s by American Specialty Insurance Company. They were the first to be concerned about increasing injuries in MLB. It was only given to MLB Front Offices and not the public. I used this data for my first published medical article in 2001, Disability Days in Major League Baseball.
As people who have worked with me will tell you, the end of the season brings a multitude of excitement for me. If you are fortunate enough to make the playoffs, it is the thrill of potentially making it to the World Series and the fun of receiving all the Gatorade products the company sends you for the playoffs. For teams that don’t make the playoffs, it is the finality that a disappointing season is finally over and you are able to reset and hope for a better season next year.
For me it also involves the excitement of going over the final numbers of the Disabled List. OK you may think that I am a bit weird. I would like to call myself a DL Geek but I realize I am too old and not smart enough to deserve the title of Geek. But I enjoy looking at the trends and nuances of the DL as one of the proxies for injuries in Major League Baseball.
We have gone over the strengths and weakness as well as limitations of the MLB Disabled List in a previous article on Hamstring Injuries. As a reminder, the strength of the DL is the historical perspective it gives us relative to the past 20 plus years as the rules (other than the concussion DL) have remained stable since at least 1989.
Let’s look at those previous DL numbers since 1998 that were chronicled in an article that we authored earlier this year, Injury Trends in Major League Baseball: 1998-2015.
NEW MLB DL RECORD
The hamstring article showed a “record” number of DL’s for hamstring strains in 2016. This was a small indicator that this also may be a record year for all injuries in Major League Baseball. And that proven to be correct.
2015 had eclipsed previous records for Placements (also called Observations or Obs), Days lost to players on the DL (DL Days) and Dollars lost to salary and replacement cost for players on the DL.
Before we get into the numbers, let’s make sure we are all using the same numbers and definitions:
Observations: This is the number of times teams used the DL to call up another healthy player. If a player went on the DL, recovered and played and subsequently went back on the DL for the same or different injury, that counts as two placements in my system. In some people’s mind that is only one because it is the same player. I see it differently as the player either sustained a new injury or re-injured the previous injury. It makes no difference; I see that as two DL placements.
Days Lost: The is from the time he went on the DL until the day he was reinstated on the MLB roster. What about rehab games? Some would say that a player was able to play while he was playing rehab games in the minor leagues. While on the DL, a pitcher can spend up to 30 days to rehab in the minor leagues while position players have only 20 days. After they complete the maximum days, they must be reinstated to the MLB roster with a few exceptions. I include those rehab days as part of the lost days since the player was not able or the team did not think he was ready to compete at the Major League level. Some players are reinstated from the DL after rehab and then immediately sent back to the minor leagues. The DL days would be the same for all and this is consistent in the tallying of the DL lost days.
DL Dollars: This is a pro-rated amount based on the player’s guaranteed salary. I count a complete season as 183 days. Some could argue that is 182 or 184 but I have used 183 consistently for all the years of calculations. So for example, if a players makes $1,830,000 per year and misses 100 days, his DL costs his team $1,000,000: Formula: (1,830,000/183)*100 days.
What about replacement costs. The entire idea of the DL is to get a healthy player to replace the injured player. Many times, but not always, it is a minor league player that is called up. By the Collective Bargaining Agreement, that called up player has to be paid the MLB minimum salary. This number has changed over the years and in 1998 was $170,000. It is now in 2016, $507,500. To see the minimum salaries from 1970-2015 click this link. I have used the minimum salary for each year to determine the minimum replacement cost based on DL days lost. We know that this is undervalued and is probably much more than that but it is the minimum a team would have to play to replace the injured player. Again, the key is to be consistent from year to year on the calculations.
In the previous 2015 record year, the number of placements was 536 with 30,302 DL Days and $694,835,359 in DL Dollars including minimum replacement costs. Those at the time, set all-time MLB records. Let’s compare that to 2016 numbers.
DL Placements for past 7 seasons:
So the number of players placed on the DL in 2016 exceeded the previous high in of 536 by 25 more players indicating a 4.1% increase. What is more astonishing is that it is a nearly 24% increase since 2010.
To get a better idea of the continued upward trend in the number of placements over the years, the following is a graph dating back to 1998. 1998 was chosen principally because that is the first year that there were 30 teams in the league, which has remained stable in the past 19 seasons.
For those of you that are in to analytical stats, this trend line is statistically significant with a p value = .000029 (anything under .05 is significant) and a r2 = .65.
DL Days Lost for Past 7 seasons
DL Days Lost for Past 7 seasons
Again, there is another record number of DL Days compared to the previous record in 2015. This is nearly a 4.5% increase from 2015 and a staggering 34% increase since 2010. In addition, this is only the second time that the number of DL Days has surpassed the 30,000 watermark.
Below shows the DL Days Lost dating back to 1998:
This trend is also highly statistically significant with p value = .0005 and a R2 of .51.
What about DL Dollars?
First, DL Dollars are not always comparable from year to year like Placements and Days Lost. This is because average player’s salaries continue to increase each year and the minimum salaries increase as well. This makes it more difficult to compare over time. But let’s look at them as we did with Placements and Days Lost.
As you can see, 2016 Total DL Costs were below the 2015 high by about $24 million. Even there were significantly more DL Days in 2016 than 2015, less money was spent on salaries of players who didn’t play because of injuries. This is because many times the total lost dollars by the DL is more about who gets injured rather than how many get hurt. If more high salaried players go on the DL this will increase the dollar amounts and those could inflate the numbers. Personally, I do not like reporting these numbers since it doesn’t tell the whole epidemiological story but it does put into dollars the need for prevention and avoiding long DL stints.
However, increase in player’s salaries only explains part of the upward trend in Total Costs. Looking at the increase in average player salaries since 1998, we see a 395% increase. When looking at the percentage change in DL Dollars from 1998 to 2015, we see a significantly larger increase in this number to 509%. This indicates that the increase in DL Dollars has been steeper than the average MLB salary
Conclusion
The number of placements and days lost to the DL have continued to rise with 2016 hitting record numbers in spite of 2015 being a record year prior to 2016. There continues to be statistically significant upward trends in injuries as measured by the Disabled List. DL Dollars were down by $24 million dollar compared to 2015 that represented a 3.5% decrease. However, this still was the second largest lost dollars in MLB history.
Our next blog will go deeper into this data to look at injuries by position and diagnosis for 2016.
Hamstrung!
MLB sets new record for Hamstring DL’s
Stan Conte PT, DPT, ATC
(The term “Hamstrung” actually originates from Biblical writings and referred to ancient warriors cutting the hamstring tendons of their enemy’s horses so they could not be used in battle)
I received an email in early June from Jeff Zimmerman, a baseball injury blogger for several internet outlets including fangraphs.com. He asked me the following: “What is up with all the hamstring injuries? Cooler weather?”. I told him that I did not know but I would take a look. I have been following the hamstrings since.
There are several factors or questions that come into play in trying to answer that question.
Where do you get Injury Data?
It is important to determine what injury data is being used in the analysis. There really are only two sets of data that are available. The first and most public, is the Major League Disabled List (DL). This can be obtained from several public sources (spotrack.com is one of the better ones). I have collected DL stats going back to 1991 through various sources. DL data is the most historical and the rules for placement on the DL have remained constant over the years except for the 7-Day concussion DL that was instituted in 2010. This allows us to compare years. 1998 is a good year to start a study since the number of teams (30) have been constant since that time. That gives us 18 seasons of reasonable data for comparisons. I and others have used this data for several published studies including a recent study in The American Journal of Orthopedics (see graph below). However, there are several problems with using this data. The first and foremost is that the DL is NOT an injury database. It is a roster management tool to replace injured players on the 25 and 40 man rosters and thus protecting them from being claimed by other teams through a waiver claim process. Therefore, all the data on the DL may not be precise or even correct and it includes only Major League players.
The other potential database is from the Electronic Medical Record (EMR) System that was established by an agreement between MLB and the Players Union in 2010. Athletic Trainers from every team and at nearly every level of play enter injury data in this system daily. De-identified injury data from the EMR, can be extracted through a database called the HITS system. Through the use of this system, injury data can be obtained that is more accurate and granular than that of the DL. In addition, the HITS system includes major and minor league injury data. There are few issues with this system in looking at the historic trends of hamstring injuries. One is that the data only goes back to 2010. In addition, one can only obtain this data if you are connected with a major league organization and 2016 data will not be available until several months after the end of the season.
Because of these reasons, I decided to utilize the Disabled List dating back to 1998 as my reference to see if there has been an increase hamstring injuries. Below is a chart showing the DL Days accumulated for all teams by years 1998-2015.
There are several factors or questions that come into play in trying to answer that question.
- What is the “normal” amount of hamstring injuries in a season?
- What was the average number of hamstring injuries per month in order to project where they might end up.
- What data is available and which data should be utilized.
- Are there other studies that can answer these questions?
Where do you get Injury Data?
It is important to determine what injury data is being used in the analysis. There really are only two sets of data that are available. The first and most public, is the Major League Disabled List (DL). This can be obtained from several public sources (spotrack.com is one of the better ones). I have collected DL stats going back to 1991 through various sources. DL data is the most historical and the rules for placement on the DL have remained constant over the years except for the 7-Day concussion DL that was instituted in 2010. This allows us to compare years. 1998 is a good year to start a study since the number of teams (30) have been constant since that time. That gives us 18 seasons of reasonable data for comparisons. I and others have used this data for several published studies including a recent study in The American Journal of Orthopedics (see graph below). However, there are several problems with using this data. The first and foremost is that the DL is NOT an injury database. It is a roster management tool to replace injured players on the 25 and 40 man rosters and thus protecting them from being claimed by other teams through a waiver claim process. Therefore, all the data on the DL may not be precise or even correct and it includes only Major League players.
The other potential database is from the Electronic Medical Record (EMR) System that was established by an agreement between MLB and the Players Union in 2010. Athletic Trainers from every team and at nearly every level of play enter injury data in this system daily. De-identified injury data from the EMR, can be extracted through a database called the HITS system. Through the use of this system, injury data can be obtained that is more accurate and granular than that of the DL. In addition, the HITS system includes major and minor league injury data. There are few issues with this system in looking at the historic trends of hamstring injuries. One is that the data only goes back to 2010. In addition, one can only obtain this data if you are connected with a major league organization and 2016 data will not be available until several months after the end of the season.
Because of these reasons, I decided to utilize the Disabled List dating back to 1998 as my reference to see if there has been an increase hamstring injuries. Below is a chart showing the DL Days accumulated for all teams by years 1998-2015.
Other Studies on Baseball Hamstring Injuries
One of the more recent and comprehensive studies on Hamstring Injuries in professional baseball was authored by Dr. Christopher Ahmad, the NY Yankee Orthopedic Team Physician. This study, Major and Minor League Baseball Hamstring Injuries: Epidemiologic Findings From the Major League Baseball Injury Surveillance System
was published in 2014 in the American Journal of Sports Medicine. The study utilized the HITS system and reported hamstring injuries in the 2011 season. He reported that in the 2011 season there were 50 major league and 218 minor league players who sustained hamstring injuries, missing an average of 24 days and 27 days, respectively. The study also showed that the highest number of strains occurred in the month of May.
Hamstring DL Placements 1998-2015
Let’s look at some historic data on hamstring injuries. The total number of players placed on the DL from 1998-2015 was 621. The number per year averaged 34.5 per season with a low range of 24 in 1998 and 2011. The highest recorded year was 48 placements in 2014. See table below
The graph below indicates a very slight upward trend increase of Hamstring DL placements over the years but this was not statistically significant with a p value = 0.41 and standard deviation of 6.83. This shows wide variations from year to year with almost an undulating pattern.
Hamstring DL’s by Month
Ahmad’s hamstring article showed that the month of May had the highest incident of hamstring injuries and this is further demonstrated utilizing the DL.
Notice that DL placements in March and September are included in this table but both of these months are deceiving. This is because of the limitations of the DL. March typically includes only the last 7-10 days of the month. This is because the start of the Major League season is on or around April 1st. The rules of the DL allow teams to retroactively place injured players on the DL eight days prior to the beginning of the seasons. There certainly are hamstring injuries and injuries of all types, that occur in spring training but are healed and the players have returned to play prior to the start of the season and therefore are not reported on the DL. September is also unique since on September 1st, all teams are allowed to expand their roster with up to 15 additional players. Therefore there is less of a need to place an injured player on the DL. This is one of the principal reason that March and September are very low DL months.
Lost Days due to Hamstring Injuries
The total of lost days due to placement on the DL for 1998-2015 was 20,090. This was an average of 34.5 days per injury. This differs from Ahmad, et al, results that showed in the 2011 season only 24 days were lost to hamstring injuries. There can be several reasons for this difference. One is that the DL has a minimum of 15 days on every DL while the HITS data will more accurately show players that lost only 1 to 14 days thus bringing the average down. However, if the hamstring injury is severe enough to be placed on the DL, the average stay on the DL is 34.5 days. The second reason maybe because 2011 was a low DL year for hamstring injuries showing only 24 DL placements. This was one of the two lowest DL placements in the 18 seasons studied. Also, 2011 had one of the lowest average stays on the DL with 22.9 days. This is in comparison to highs at 46 in 2001 and 2005.
How does all of this compare to 2016 numbers?
As of 9/17/16 as indicated by the table below, there have been 53 placements of hamstring injuries on the DL. This surpasses the previous high of 48 hamstring DL placements in 2014. It also demonstrates the two highest levels of hamstring DL’s ever in two of the last three seasons. Also note that most of the months in 2016 were higher than the previous averages with June being very significant.
Re-Injury Rates
Ahmad, et al, reported a 20% re-injury rate in 2011 based on the HITS data that included major and minor league players. This is a high re-injury rate. As way of comparison, Oblique injuries have a 8-10% re-injury rate. Our study here using only MLB players on the DL for the past 18 seasons revealed that out of 621 Hamstring injuries, 103 had at least one recurrence of a hamstring strain. Further break down of the 1998-2015 DL by players shows 78% (N=357) never had a recurrence vs. those with recurrence regardless of side (n=103, 22%). This 22% re-injury rate is in line with the Ahmad study. For those with a recurrence, the number of players with ipsilateral (n=75, 73%), contralateral (n=56, 54%), and side unknown (n=3. 3%) recurrences are provided. You’ll notice that these three numbers add up to more than 100%, but that is because some players had both ipsilateral and contralateral recurrences. The ipsilateral recurrences are then broken down by the number of recurrences. This demonstrated in the following flow chart below. This analysis was done by Dr. Christopher Camp, an orthopedic surgeon at Hospital of Special Surgery in New York. See Flow Diagram below.
Our 2016 DL data indicates that 11 players were re-injured in the 2016 season or also had a previous injury in 2015 (one player had 2 previous injuries between 2015-16 for a total of 3 hamstring DL’s). This calculates to a re-injury rate of 18% and is very consistent with Ahmads’s paper’s conclusion of a 20% re-injury rate.
Prevention
So after all this data, what can we do to decrease hamstring injuries in baseball? Is there a successful prevention program? We need to look to the European soccer leagues to find the answer. Hamstring injuries are very prevalent in European with one study indicating that 80% of all soccer injuries occurred in the lower extremity and that 47% of them were hamstring strains. (Askling, et al, Scand J Med Sci Sports. 2003). This study and others have shown that instituting eccentric hamstring strengthening exercises decreased their prevalence. So why don’t we do that with baseball? One team did exactly that. The Los Angeles Angels just recently did a study where they implemented the strengthening program in their organization and 213 of their players. They found a 25% reduction in major league injuries and a 40% reduction in minor league injuries compared to a control group. In addition, those that did get injuries lost less time and recovered faster than the control group. Many teams have implemented this program and hopefully we will see an overall reduction in hamstring injuries.
Conclusion
After looking at all the historic and current DL that resulted from hamstring injuries, we see that 2016 is a MLB record year for players placed on the DL with 53 total. This also shows that that during the past 3 seasons, 2014 and 2016 had the greatest number of hamstring injuries resulting in DL in the past 5 years. Even though the overall trend over the past 18 seasons does not show a statistically significant increase, there is a trend upward. The re-injury rate utilizing the DL is similar to the Ahmad study utilizing the HITS system. It further indicates the best predictor of a future hamstring injury may be a previous hamstring strain. The final question is of course, why? To this question, I do not have a reasonable answer other than as we have seen, all injuries are pointing upward especially in 2015 and 2016 and hamstring strains are part of that group.
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