Terminal Velocity: Quantifying Pitcher’s Elbow Injury Risk as a Function of Fastball Variance

Pitching injuries are the biggest hazard in fantasy baseball, and elbow injuries are the number one. What if there was a way to objectively quantify who is most and least likely to suffer such injuries?

We know that maximal effort is the leading cause of elbow injury. To be clear, not how hard you throw, but throw as hard as you can throw, as fast as it can be. We also have excellent velocity data for all launchers. What if we stipulated that throwers whose average speed is closest to their maximum speed throw more frequently with maximum effort? Conversely, those with their average furthest from their top speed are less likely to put everything into their bids. This gives us a green light and a yellow light (maybe a red light depending on how persuaded you are here) when evaluating pitchers.

Before we release the list based on 2022 speed data, let’s expand the thesis a bit with the help of top medical expert Glenn Fleisig, director of biomechanics research at the American Sports Medicine Institute (ASMI ). In 2017, I also used speed data in an article for the Wall Street Journal about the rise in career-threatening elbow injuries.

Here is what Dr. Fleisig told me then for this article:

“If a guy peaks at 96 and throws the whole game (there), he’s adding a lot more stress on his elbow than if he’s varying his speed,” says American Sports Medicine Institute research director Dr. Glenn Fleisig .

Dr. Fleisig likens the ligaments in the body — like the one in the elbow that tears and forces pitchers to miss a season recovering from Tommy John surgery — to a rubber band. Pull it as hard as you can and it will start to tear. Pull less, he says, and “you’d never tear the rubber band.”

I recently confirmed with Dr. Fleisig that this is still the operative theory for elbow injuries. He also said that a max-minus-average metric like the one we used in this article is still a reasonable way to assess relative risk.

The data we use here is different. Next, we had the max and average speed for the whole game. Now we have more apples to apples comparisons in different height strata (slots 1-20, 21-40, 41-60, etc.) via SimpleBet, which uses machine learning and real-time technology to “make every moment of every sporting event a better opportunity. (This data is collected to inform bettors about the speed of the next pitch for a specific pitcher. But we use them here to assess injury risk for the upcoming season.)

The lower end of the speed gap between maximum speed and average speed is about two miles per hour or less. Top of the range is around four mph or so. Again, more of the gap between max and average means the pitcher isn’t maxing out their fastball as often, and less means they’re probably pitching full tilt more often, leading to a greater risk of injury.

To be clear, any pitcher can be injured on any pitch. We want everyone to be healthy. It is simply an attempt to merge the science of elbow injuries with the hard data, as best we currently can. It’s not binary – I’m not saying some guys are safe and some guys are on borrowed time. It’s not black and white. It’s just a question of probabilities. Who throws optimally according to elbow injury science and who throws suboptimally?

When we performed a similar (but not identical) analysis in the Journal in 2017, the pitchers who were identified as having greater elbow risk were: Steven Matz (later elbow surgery in 2017), Noah Syndergaard (later surgery Tommy John in 2020), Michael Fulmer (Tommy John surgery in 2019), Jameson Taillon (Tommy John surgery in 2019), Stephen Strasburg (subsequent elbow conflict in 2017). However, safe pitchers did not fare very well. Carlos Martinez had unrelated shoulder surgery (according to science) and Chris Sale had Tommy John surgery in 2020 (but that was after 1,629.2 career innings, far more than anyone in the group at risk that has been identified).

Here is the data list for 2022, again courtesy of SimpleBet.


Let’s look at the guys who get the green light.

Freddy Peralta is red flagged for injury in our game, but his issues have involved the shoulder, a different type of injury not covered in this analysis. We’re just giving his elbow the nod given he’s the best right now at varying his speed. And again, it’s not because it loses velocity as the number of pitches increases since it’s the average of the max versus the average across all 20-pitch strata ( 1 to 20, 21 to 40, etc).

Max fried does it the right way. I love this approach for such a young pitcher and also think, and this is without data, that varying fastball speed is actually a good fastball strategy. (I want to point out that maximum effort on any court, Dr. Fleisig recently taught me, is a precursor to elbow injury – we just use fastballs because we have the most data on them. .)

Michael Kopech previously had Tommy John surgery. Maybe he’s varying his speed accordingly, or maybe it’s his plan to avoid a second reconstructive surgery, most likely a fatal blow to his career.

I don’t want to do too much David Peterson because some relief sleeves are mixed up here. But looking at the pitches in the pitch number range alleviates the issues here. Peterson can throw shockingly given his reputation, but that shouldn’t be a problem given his solid fastball variance.

Shohei Ohtani can also fit a previous Tommy John operation. If that’s his answer, it’s obviously a very good answer that the medical community generally supports. Again, in the old fashioned way, Ohtani’s elite speed would be a big concern, but this approach proves he can throw much harder than average, reducing worries about elbow stress.

Carlos Rodon is here ironically as he now has elbow issues. We can’t give him a green light obviously, but I’m not going to give him a red one since he’s apparently trying to fluctuate his effort when he throws. The bottom line is that if you drafted Rodón in his post-injury ADP, that data indicates you made a reasonable bet.

Nathan Eovaldi also has a long injury history but has avoided elbow issues since 2019. He’s good when healthy and Rangers could be a good team so I like his 200+ ADP even more given those data. But, remember, he had shoulder problems in 2022.

Kevin Gausman is like the new Justin Verlander in the way he proactively varies his speed. Maybe that’s why he can survive as a two-pitch pitcher with the splitter, even though the fastball wasn’t very effective according to Statcast last year. Still, the overall pitching arsenal works.

Robbie Ray gets Ks without maximum effort, maybe that also improves his control. same for me Gerrit Cole, which resembles a horse in the way it defies the odds of injury – and it gives us a window into why. Verlander has always been the modern poster player to dial in the fastball when needed. He still does after returning from career-ending Tommy John on his way to having arguably his best season yet.

Spencer Strider And Yu Darvish are in the safe zone. Strider has height issues (really just height, since he’s built like a wrestler). You would think it maxes out to generate its average over four seams, but you’d be wrong. Darvish is so underrated from his 2022 season. He throws seven pitches and that’s not even including those variable speed fastballs.


I have a part of post-oblique Tyler Glassnow somewhere and now I wish I hadn’t. I’m afraid the elbow will bark periodically, although the recency of the operation probably precludes another tear. He’s just not doing himself a favor. I know last year’s data sample was small, but how much do you need? It’s probably maximum effort.

While hunter brown was sidelined with a back injury, I’m worried about his elbow. Remember, it throws sliders at 93 mph and their max is also terrible. Add the extra adrenaline of being in the majors and I’m afraid the rubber band will stretch too much if it breaks.

Jacob of Grom is programmed to throw 100 mph on every pitch. It drove me crazy when I watched it here in New York. You don’t need to go all-in on at least half the batters. He should calm down. This is the main reason to expect another move to DL this year.

I think the park is the main reason not to draft Nick Lodolo. But his max-minus-average gap is so small. For comparison, Hunter Greene is 3.3 mph, about 50% faster. Greene throws harder but his elbow poses less of a risk than Lodolo’s.

Similar to Glasnow, I don’t think Dustin May learned his lesson. The Dodgers are all-in apparently on maximum effort. You have proof of that last year with Walker Buehler before his Tommy John surgery, and Clayton Kershaw seems to be maxed out. And even Washington’s Josiah Gray (2.3 mph) grew up in the Dodgers’ system.

Jeffrey Springs is a sabermetric darling. All the analytics guys love Springs. I have stocks. I wrote about him as a bargain before his ADP skyrocketed, especially in the high stakes leagues. But I issue a small warning here. I’m not saying Springs is going to get hurt, but he’s shaping up to be a pitcher who maximizes/attempts elbow woes.

The last guy is Lance McCullers Jr. His 2.5 mph wouldn’t be all that remarkable, but it’s just on the verge of worry and he already has an elbow problem. So expecting him to recover and then throw hard most of the time is just too risky, even with his depressed ADP.

(Top photo: Ben Ludeman/Texas Rangers/Getty Images)


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