Major League Baseball's Latest Crisis: Starting Pitcher Injuries
High profile starters are dropping like flies with major elbow injuries. Here is why...
Baseball is facing an epidemic in the form of starting pitcher elbow injuries. It’s like Queen’s hit “Another One Bites the Dust” has been playing on repeat in this young MLB season. So far, we have seen stars Framber Valdez, Gerrit Cole, Shane Bieber, Spencer Strider, Sandy Alcantara, and Tony Gonsolin, among other pitchers, hit the injured list with elbow injuries. They join stars Jacob DeGrom, Felix Bautista, and Dustin May who are still sidelined from elbow injuries last year, along with two-way superstar Shohei Ohtani who will only hit this season while his elbow recovers from Tommy John surgery last fall. That list alone accounts for 23 All-Star appearances, 5 Cy Young awards, and 2 MVP awards. The majority of these injuries have been to the Ulnar Collateral Ligament in the elbow, and the most have resulted in (or will result in) major, highly invasive surgery. Ulnar collateral ligament reconstruction, or more familiarly “Tommy John Surgery”, is a procedure in which the ulnar collateral ligament (UCL) in the elbow is replaced with a tendon either from elsewhere in the body or from a deceased donor. Tommy John surgery has been on the rise in recent years. Between 2021 and 2023, 94 Tommy John surgeries were performed on MLB pitchers. That is up from 76 between 2018 and 2020. To put this into perspective, in 2010 and 2011 just 17 Tommy John Surgeries were performed in each year. MLB Player’s Association Executive Director Tony Clark called out the pitch clock as a major factor behind the spike in pitcher injuries this season. But this has not just been a “this season” thing, this has been building for years. The numbers back this up and may help us understand why.
Velocity
Something else has been rising alongside Tommy John surgeries; fastball velocity. The chart below shows the increase in average fastball velocity (in MPH) since 2010.
The human arm simply cannot sustain the strain of throwing with this intensity at the repetition required for a starting pitcher. Something had to give, and that something has been duration. Starters are going less and less deep in games, nearly in lock step with the rise in velocity. In fact, there is nearly a -0.91 correlation coefficient between average MLB fastball velocity and average number of innings pitched per game by a starter. This essentially means that as fastball velo increases, there is a near-perfectly linear decrease in IP/G by a starter.
As you may expect, this results in fewer pitches per game by a starter. The correlation coefficient between pitches per game and average fastball velocity is nearly just as strong at -0.89.
So, what does this all have to do with Tommy John surgeries and elbow injuries? As we know, correlation does not imply causation, so who’s to say this extra juice in the fastball is hurting elbows? To answer this, I decided to look at pitchers who’ve suffered elbow injuries and pitchers who have not separately. Specifically, I looked at Statcast data dating back to 2017 of pitchers who have had Tommy John against pitchers who have not1. Do note that I grouped pitchers who sustained UCL/elbow injuries of any type in 2024 into the injured group, as for many it is yet-to-be-determined if they will need Tommy John (regardless, they all will surely be out for significant time). The Tommy John pitcher had an average fastball velo of 94.65 MPH, while the non-injured pitcher’s average fastball was 93.24. Based on a t-test, this difference is statistically significant with a p-value of essentially 0, remember that a p-value below 0.05 represents statistical significance (if you want to get technical the p-value was 3.137e-12). Quick stats lesson for those so inclined - the p-value represents the probability of a difference this extreme occurring strictly by chance (i.e., no actual difference between the variables). Pitchers who suffered UCL injuries which required, or may require, Tommy John were statistically more likely to throw harder.
Spin Rates
Velocity is only one aspect of pitching; movement is just as important, if not more. Spin rates have been all the rage of late. Beginning in 2021, the MLB has had to crack down on pitchers using “sticky stuff” to get a better grip on the ball to try and get more spin. MLB.com explains spin rates nicely:
“The amount of spin on a pitch changes its trajectory. The same pitch thrown at the same Velocity will end up in a different place depending on how much it spins (For instance, a fastball with a high Spin Rate appears to have a rising effect on the hitter, and it crosses the plate a few inches higher than a fastball of equal Velocity with a lower Spin Rate. Conversely, a lower Spin Rate on a changeup tends to create more movement.)” - MLB.com Statcast glossary
While this crack-down has helped revive some offense in the game, it has possibly had a negative impact on pitcher’s elbows. Even though “sticky stuff” is off the table now, the importance of spin on the ball has not been reduced. This has caused pitchers to resort to other means, such as gripping the ball differently. Tyler Glasnow, starter for the Los Angeles Dodgers claimed, “I had to put my fastball deeper into my hand and grip it way harder…I’m choking the (expletive) out of all my pitches“. Glasnow’s comments came after he stopped using sunscreen, the only foreign substance he claims to have ever used on his hands, amid MLB’s crackdown. After doing away with the sunscreen, Glasnow pitched against the Nationals and immediately felt extra sore in his elbow; “I woke up the next day and I was sore in places I didn't even know I had muscles in.". Very soon after, Glasnow was diagnosed with a partially torn ulnar collateral ligament and a flexor tendon strain. He would have Tommy John surgery just two months later.
It is clear when looking at the numbers that pitchers with greater spin rates on their fastballs have a greater risk of UCL injuries. The average spin rate of a pitcher who has had Tommy John is 2,284.6 RPMs, for a pitcher who has not their average is 2,254.42. This difference is statistically significant with a p-value of 0.0084.
Ultiamtely, we have determined that pitchers who end up needing Tommy John surgery have both significantly higher fastball velocities and spin rates.
The Pitch Clock
What about Tony Clark’s claim about the pitch clock? Sorry Tony, but your argument doesn’t hold up. Among pitchers who have thrown at least 100 pitches in each season from 2017-20243, those who got Tommy John actually have a SLOWER tempo (measured by time between pitches). The Tommy John pitchers averaged 17.54 seconds between pitches, while the healthy pitchers averaged 17.48 seconds. If anything, you could argue the pitch clock has helped (although sometimes you have to pick and choose your battles). Regardless, the institution of the pitch clock and subsequent speeding up of the clock this year seems to be of no concern when considering elbow injuries.
How do we fix this?
There is no question that, for the good of the sport, we cannot continue on this trend. Some have offered suggestions, such as limiting the number of pitchers allowed on an active roster. ESPN Baseball Insider Buster Olney toyed around with the idea of tying the Designated Hitter to the starting pitcher, in which the team would lose their DH after the starter was removed. Personally, I think incentivizing the starting pitcher going longer may be the best route. Maybe we say that if a starter pitches less than 6 complete innings the team loses the DH for the rest of the game (forcing pitchers to hit in that case)? Or maybe incentivize pitchers staying healthy by tying compensation to pitchers’ health by way of a monetary penalty for time served on the IL, or a bonus for completing a season without landing on the IL. Alternatively, MLB could look into altering the baseball (which we all know goes on anyway) to give it a better grip so pitchers don’t feel the need to, as Tyler Glasnow elegantly put it, “choke the *bleep* out” of the ball. I fear though that at this stage it is still too attractive to try to throw hard and put spin on the ball, because that is what brings success. Are these young pitchers coming up through high school, college, and the minors going to say, “well I can throw 95 and spin it, but I’m going to throw slower and flatter to save my elbow, even though Johnny on the other team is still throwing 96”. Absolutely not! They are going to do whatever it takes to beat their competition and make it to the big leagues. Unless some intervention is made, this injury problem will grow until pitchers have more to lose than to gain in this approach to pitching. I hope this changes or some positive intervention is made, because the path we are going down is a dark one, and I don’t see an end in sight.
Based on Statcast data, minimum 250 pitches thrown each season.
Based on Statcast data, minimum 250 pitches thrown each season
Based on Statcast data, minimum 100 pitches thrown each season.