Batter Results After Tommy John Surgery
Tommy John surgery week continues with the hitter edition. With both Riley Greene and Jasson Domínguez (Shohei Ohtani got the brace procedure) getting a Tommy John surgery, I wanted to know how their performance changed from when they were healthy, to hurt, to fixed.
Note: I’m pushing my limits on what I’d like with a sample was 26 hitters. Sometime the matched seasons doesn’t lineup thereby pushing the number even further down. I understand if someone feels the sample is too small and blows off the results.
I found the change by using a weighted change from season to season. The hitters who had the most matched plate appearance got the most weight.
Since 2005, I found the hitters’ stats in four different seasons
- Year 1 (y1): The season before the injury. This season should provide a baseline talent.
- Year 2 (y2): The season of the injury.
- Year 3 (y3): The season returning from injury.
- Year 4 (y3): The season after the season returning from injury where the hitter is hopefully 100% healed.
And here are the results:
| Seasons | Matched PA | K% | BB% | ISO | AVG | OPS | Count |
|---|---|---|---|---|---|---|---|
| y1 to y2 | 3604 | 1.7% | -0.9% | -.021 | -.028 | -.081 | 16 |
| y2 to y3 | 3219 | -1.3% | 0.6% | -.014 | .015 | .020 | 19 |
| y3 to y4 | 5388 | -1.0% | -1.1% | .005 | .004 | .004 | 19 |
| y1 to y3 | 6446 | 0.8% | -0.2% | -.024 | -.006 | -.037 | 22 |
| y2 to y4 | 2450 | -2.2% | -0.1% | -.012 | .018 | .021 | 14 |
y2 = season of surgery
y3 = season returning from surgery
y4 = season after season returning from surgery
Again, how much these small sample stats are used is up to the reader. Here is how the narrative would play out if the results can be believed.
The hitters take a major hit from their healthy season (y1) to the season they have the surgery (y2). An 80-point hit in OPS is equivalent to a 20% drop in overall production with the decline happening across the board. When the hitters are healthy, most of their production returns except their power as seen from y1 to y3 and y2 to y3. Finally, they don’t see any major gains once healthy.
The above changes follow Bryce Harper going from a 1.044 OPS in 2021 to a .877 OPS in 2022 (surgery season) and a .900 OPS this season when he returned. If he follows the overall trend, he should remain productive next season but he probably won’t get to previous levels.
One explanation for the limited rebound is that the injury stats are over a four-year span and the average hitter would be past their age 26 season and on a decline. Between the injury and normal decline, it’s likely that any hitter who had a Tommy John surgery already had their career peak.
Also, I wanted to run the numbers with the StatCast data but the sample was 11 hitters. With some of the matched seasons not lining up, the number was just a half dozen. I won’t be looking into those numbers right now.
The results should not come as a surprise, but at least some numbers can now be put with the expectations. Just one more study Tommy John study to go, those pitchers with multiple surgeries.
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 four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR twice, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.
What I’m taking away here (which could be totally not what Jeff intended) is that by the second year after surgery, the player is generally back to pre-surgery levels once age related decline is taken into account. It will be interesting to see what happens with Jasson, since age related decline is obviously less of an issue for him.
It could be that, or it could be that the injury lops off a portion of your peak if you remained uninjured at all. Another interesting study: Do player who start to get hurt early on, tend to continue to do so? Obviously, some do, some don’t.
The most relevant comparison for Dominguez is probably another Yankee, Gleyber Torres. Torres had Tommy John surgery in June 2017 at age 20. He made his major league debut 10 months later, in April 2018. He played 123 games that year and hit .271/.340/.480, and then in 144 games in 2019 he hit .278/.337/.535.
Obviously it remains to be seen how Dominguez will recover, but the surgery didn’t really seem to hamper Torres much at the same age. His value should be propped up by the fact that he was a 15% BB guy in the minors with tons of value on the basepaths. If he can come in and hit .250/.375/.450 the Yankees will be over the moon.