Playing Through an Injury Hurts Future Performance

I was wrong. About seven years ago, I wrote on how hitters may overperform their projections since they played through an injury. The injury hampered their production in the season in question, lowered the future projection, and created a buying opportunity. For years, I believed this steadily until last season when I re-ran the numbers and found “jack squat”.

Earlier this week, I examined some of this past season’s hitters who fought through the pain and felt a deeper analysis was needed. I dove in and the results were backwards. I found no bounceback should be expected from hitters who played through injuries, but there is more. For those hitters who play through the discomfort, their future production will take a major hit.

The key to uncovering the following results was getting a usable dataset which is easier said than done. Many of the injuries I’m using for the analysis aren’t well documented, if at all. Real men play baseball and they play hurt because that is what real men do and most importantly, they don’t complain about. Besides the machismo, a player has every right to keep his medical data to himself so vagueness thrives. Simply, there is no good available data. Even with the hurdles, I dug into each of the hitters who were reported to have played through an injury the past three seasons (2017, 2018, 2019).

For all three seasons, I went back and read through the linked article for the date and details of the injury. In many instances, I had to go to RotoWire and comb through the old news and I can’t thank them enough for providing this resource. For each player, I tried to find the exact date of the injury along with the following OPS values (*):

  • Steamer Projection for the season the injury occurred
  • Before the injury
  • After the injury
  • Steamer Projection for the season after the injury
  • Results for the season after the injury

The in-season analysis utilized all three years of data and the next year’s analysis excludes the 2019 data. In some instances, the injury happened in Spring Training or immediately into the regular season and no before-and-after data exist. That’s enough background, it’s time to dive in.

The first comparison is how the hitters performed before-and-after the injury during the season of the injury.

Change OPS From Before and After the Injury They Played Through
Season Average Median Count
2017 -.121 -.157 13
2018 -.074 -.077 24
2019 -.101 -.118 20
Total -.094 -.099 57

The performance drop is noticeable and consistent across the three seasons. For fantasy owners, they need to be wary if they hear a hitter is banged up and should expect a noticeable performance decline.

Next up is how these hitters performed compared to their preseason Steamer projections. Besides the overall numbers, I divided up the players into those who were hurt the entire season and those for just a fraction of it.

Difference in OPS From Projection to the Season They Played Through the Injury
Average Median Count
All -.017 -.016 69
Full Season Injury -.058 -.085 13
Partial Season Injury -.008 -.015 56

No surprises appear in the above data since those hitters who had the injury longer saw more of a decline.

And now for the money table. Here is how the hitters hit in the season after the injury. While I did split the data up some, I feel the sample is too small to split a split. Maybe in the future more can be done. Additionally, I created a metric out of thin air to help determine how much the injury may have hampered the player. In the end, I decided on:

Injury Effect = (Days from Injury to End of Season)/183 x Change in OPS * 1000

I used -40 as the dividing point between “Short & Little Effect” and “Long & Large Effect”. I know it’s not close to perfect but it at least gave me a way to divide up the players.

Difference OPS for the Next Season’s Projection & Results
Average Median
Sample Act–Proj in Y1 Act–Proj in Y2 Age in Y2 Act–Proj in Y1 Act–Proj in Y2 Age in Y2
Short & Little Effect .010 .008 29.3 -.010 .034 29.0
Long & Large Effect -.029 -.035 28.7 -.033 -.017 28.5
Injury Full season -.063 -.038 28.7 -.087 -.034 28.0
Under 30 Years Old -.026 .014 26.5 -.016 .025 27.0
30 Years and Older -.039 -.073 33.3 -.039 -.049 32.0
All -.030 -.017 28.9 -.022 -.009 29.0

So the results are completely opposite to what I thought for years, playing through an injury doesn’t mean a rebound is coming the next season. Additionally, the players who played through a more severe (measured in OPS decline) injury longer, experienced even more of a decline than those who had a small injury for a short time.

Unsurprisingly, the hitter’s age matters. The younger players are able to main the projected stats. The projection already has an average aging factor incorporated into it, so the players over 30 will see a major decline. These findings follow some of my previous works where I found players who didn’t go on the DL/IL didn’t age as fast.

While I try to incorporate injury information into my analysis, I have zero medical training so I decided to elicit some expert help on the subject to see how my ideas held up. Dr. Mike Sonne (@DrMikeSonne on Twitter) believes there are two factors working against people who play through injuries. The first is that mild to moderate injuries can escalate into severe or chronic ones. Patients who put off needed rest or surgery can make the problem significantly worse.

The second factor is that the players develop alternative body movements to deal with the discomfort. The altered movements aren’t as effective and efficient as the original ones that got the hitter to the majors. When the player can finally rest and recover during the offseason, the new inefficient movements have taken hold and therefore degrade the player’s future production.

Additionally, Dr. Jesse Morse (@DrJesseMorse on Twitter) shed some insight on what any “mature” person already knows, the body takes longer to heal the older it gets. The average person heals slower starting in their early-30’s and the drop is really steep once a person reaches their mid-30’s. He emphasized several times that most baseball players are the exception to many physical rules and will exceed many norms well into their late 30’s (e.g. Nelson Cruz).

While the overall trends can be verified, Dr. Morse emphasized how each player eventually performs will be determined by the exact nature of the injury. Several times I read that a player is “dealing with a sore knee”. The soreness can be from a ligament, muscle, bone, meniscus, or some combination of each.

Going into next season, the players to worry about are listed in the table at the end of the article which includes several top picks like Trea Turner, Cody Bellinger, and Javier Báez. While the three are young, they did deal with the injury for almost the whole season. The only way to see how each player responds is to play out the season, but owners should know the downside with each.

Gutting through an injury can make an it worse and accelerate the aging process. As fantasy owners, it’s not our call to decide if the player is right or wrong for playing through the injury. We just need to know to expect less from them in the future. No rebound should be expected.

(*)

Hitters Who Played Through An Injury
Name Season Injury Location Injury Date OPS before OPS after Difference Injury Effect
Avisail Garcia 2018 Knee 04/01/18 0
Brian Dozier 2018 Knee 04/01/18 0
Kevin Kiermaier 2018 Foot 04/01/18 0
Logan Morrison 2018 Hip 04/01/18 0
Marcell Ozuna 2018 Shoulder 04/01/18 0
Matt Chapman 2018 Hand 04/01/18 0
Steven Souza Jr. 2018 Pectoral 04/01/18 0
Gregory Bird 2017 Ankle 04/01/17 0
Josh Donaldson 2017 Calf 04/01/17 0
Guillermo Heredia 2017 Shoulder 04/01/17 0
Elvis Andrus 2018 Elbow 04/12/18 0.956 0.683 -0.273 -257
Jorge Soler 2018 Rib 05/15/18 0.938 0.636 -0.302 -229
Freddie Freeman 2017 Finger And Ribs 06/01/17 1.209 0.882 -0.327 -218
Carlos Correa 2018 Back 06/06/18 0.811 0.517 -0.294 -188
Brandon Belt 2018 Knee 07/25/18 0.842 0.435 -0.407 -151
Ben Zobrist 2017 Wrist 05/27/17 0.81 0.636 -0.174 -121
Mitch Moreland 2017 Toe 06/15/17 0.864 0.694 -0.17 -100
Scott Schebler 2017 Shoulder 06/15/17 0.864 0.729 -0.135 -80
Addison Russell 2018 Knuckle 06/03/18 0.724 0.606 -0.118 -77
Xander Bogaerts 2017 Wrist 07/06/17 0.818 0.661 -0.157 -75
Maikel Franco 2018 Wrist 08/23/18 0.81 0.476 -0.334 -71
Corey Seager 2017 Shoulder 08/15/17 0.917 0.644 -0.273 -70
Jed Lowrie 2018 Leg 07/13/18 0.859 0.715 -0.144 -63
Buster Posey 2018 Hip 05/26/18 0.785 0.713 -0.072 -50
Kyle Seager 2018 Toe 06/27/18 0.715 0.623 -0.092 -48
Cesar Hernandez 2018 Foot 07/06/18 0.764 0.665 -0.099 -47
Nomar Mazara 2018 Thumb 07/14/18 0.783 0.674 -0.109 -47
Mike Moustakas 2017 Knee 08/23/17 0.876 0.67 -0.206 -44
Adrian Beltre 2017 Hamstring 08/31/17 0.946 0.713 -0.233 -39
Nolan Arenado 2018 Shoulder 08/10/18 0.974 0.838 -0.136 -39
Mookie Betts 2017 Thumb 07/17/17 0.838 0.75 -0.088 -37
Ryan Braun 2017 Wrist 07/19/17 0.872 0.787 -0.085 -34
Jose Altuve 2018 Knee 07/25/18 0.857 0.775 -0.082 -30
Byron Buxton 2018 Wrist 07/14/18 0.798 0.731 -0.067 -29
Mike Trout 2018 Finger 06/06/18 1.106 1.071 -0.035 -22
Mark Trumbo 2018 Knee 05/25/18 0.786 0.757 -0.029 -20
Travis Shaw 2018 Wrist 06/18/18 0.835 0.815 -0.02 -11
Yasmani Grandal 2017 Wrist 07/08/17 0.788 0.764 -0.024 -11
Giancarlo Stanton 2018 Hamstring 08/03/18 0.855 0.847 -0.008 -3
Salvador Perez 2018 Thumb 08/28/18 0.711 0.703 -0.008 -1
Shohei Ohtani 2018 Elbow 06/06/18 0.907 0.935 0.028 18
Edwin Encarnacion 2018 Hand 08/11/18 0.788 0.911 0.123 34
Ian Kinsler 2017 Hamstring 05/06/17 0.681 0.734 0.053 43
Rafael Devers 2018 Shoulder 06/17/18 0.698 0.78 0.082 47
Aaron Judge 2017 Shoulder 08/25/17 1.001 1.248 0.247 50
Joey Gallo 2018 Hamstring 06/22/18 0.729 0.898 0.169 93
Tommy Pham 2018 Groin & Finger 08/21/18 0.723 1.169 0.446 100
Trea Turner 2019 Finger 04/01/19
Daniel Murphy 2019 Finger 04/01/19
Gregory Polanco 2019 Shoulder 04/01/19
Cody Bellinger 2019 Shoulder 5/6/19 1.367 .950 -.417 -337
Hunter Renfroe 2019 Ankle & Elbow 6/23/19 .936 .620 -.316 -173
Domingo Santana 2019 Elbow 7/23/19 .814 .484 -.330 -126
Khris Davis 2019 Hip 5/5/19 .784 .640 -.144 -117
Alex Verdugo 2019 Back 5/15/19 .913 .771 -.142 -108
C.J. Cron 2019 Thumb 6/15/19 .865 .695 -.170 -100
Javier Báez 2019 Heal 6/1/19 .924 .797 -.127 -85
Matt Chapman 2019 Ankle/Knee 7/19/19 .918 .739 -.179 -72
Mike Moustakas 2019 Finger 4/16/19 .899 .836 -.063 -58
Marcell Ozuna 2019 Shoulder 6/25/19 .847 .739 -.108 -58
Rhys Hoskins 2019 Hand 8/14/19 .869 .671 -.198 -52
Justin Smoak 2019 Quad 6/28/19 .787 .706 -.081 -42
Mike Trout 2019 Foot 8/9/19 1.107 .972 -.135 -39
Khris Bryant 2019 Knee 7/22/19 .930 .876 -.054 -21
Tommy Pham 2019 Hand 8/10/19 .812 .834 .022 6
Nolan Arenado 2019 Toe 6/16/19 .956 .968 .012 7
Lorenzo Cain 2019 Thumb 7/25/19 .671 .726 .055 20
Yadier Molina 2019 Finger 5/31/19 .690 .727 .037 25
Max Kepler 2019 Knee 5/23/19 .792 .884 .092 66
Nelson Cruz 2019 Wrist 5/12/19 .862 1.096 .234 182

* Found out about injury after the article
Maikel Franco (link)

Brandon Nimmo, neck (link)

We hoped you liked reading Playing Through an Injury Hurts Future Performance by Jeff Zimmerman!

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Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won three FSWA Awards including on for his MASH series. In his first two seasons in Tout Wars, he's won the H2H league and mixed auction league. Follow him on Twitter @jeffwzimmerman.

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evo34
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evo34

This is great info. I’d also want to take a look at how a group of similarly-aged, normal-health players performed vs Steamer the next season. One would expect close to 0 diff. between projected and actual for this control group, but if Steamer has been overestimating offense the last couple of seasons, this might not be the case.