A Primer on Tommy John Surgery: Part Two

Matt Harvey lost his entire 2014 season to Tommy John surgery (via slgckgc).

Matt Harvey lost his entire 2014 season to Tommy John surgery (via slgckgc).

Yesterday, we looked at the explosion of Tommy John surgeries (TJS) in the major leagues, particularly the time it takes for pitchers to return from the surgery and how they perform once they return. Today, we’ll looks at the various causes and prevention methods of TJS. These areas overlap a bit, because if known causes of the injury can be determined, stopping these causes would serve as a form of prevention. As I did yesterday, I have highlighted areas for further study in italicized paragraphs labeled “Help Out.” At the end, I will give my opinion on where we stand today.

Causes and Prevention of Tommy John Surgery

This is where every discussion on the matter ends up, but it is also the murkiest of areas. Not one item can be pointed to as the exact cause of the injury. People like solutions to be simple: one cause, one effect. A catcher gets hit in the mask with a foul ball, and he gets a concussion. Simple. Unfortunately, pitchers who have Tommy John surgery don’t all fit into a single mold. If they did, the discussion would be over. Instead, I will try to go through the various theories and voids in data.

Throwing a baseball will not cause a person to blow out his ulnar collateral ligament (UCL). Position players have been playing catch for years, and they aren’t needing the surgery. So, what is unique with today’s pitchers that they need to have the surgery more often?

Before we continue, go and read the American Sports Medicine Institute’s Position Statement on Tommy John Injuries. Even if you have read it already, it is probably worth another read. It gives a basic but precise look at what they think should be done. Even though the the statement is precise and correct, more cause and prevention information is available to digest.

Tommy John Surgery Success

As we discussed in Part One, the success of Tommy John surgeries has led to more and more of them being performed. But not everyone wants to concede to needing the surgery. Unfortunately, almost all the pitchers who have recently tried to pitch through a partial UCL tear have been unsuccessful.

Mike Petriello found just four semi-recent cases–Scott Atchison, Ervin Santana, Takashi Saito and Adam Wainwright–who were able to throw with a partially torn UCL, and even Wainwright eventually needed the operation. Every other pitcher with a partial tear has gone under the knife for surgery over the past few seasons. Additionally, no one has successfully avoided surgery since 2012. Right now, a tear means surgery for an MLB pitcher.

Velocity and Pitch Type

It is tough to ignore the number of hard throwers who recently have had Tommy John surgery–Stephen Strasburg, Matt Harvey, and Jose Fernandez, to name a few. Major league pitchers are throwing significantly harder over the past few seasons.

The harder a pitcher throws, the more likely something is going to break. However, when I looked at pitchers who threw over 100 mph recently to see if they had an unusual number of Tommy John surgeries, I found no link between the two.

Help Out: While I looked at pitchers who threw over 100 mph, 100 may not me the key number. Maybe it’s 97 mph, or 95 mph. The increase in velocity and increase in TJS can’t be ignored. It is time to perform a more thorough assessment.

Pitch type could be another factor behind certain pitchers needing Tommy John surgery. As of right now, no studies point to pitch type being a cause. Going back to our old friend Jon Roegele, he found pitchers who throw hard pitches (fastballs and sliders) to be more injury prone:

The first study was aimed at determining whether pitchers on a path to Tommy John surgery throw any particular types of pitches more frequently than the average pitcher. The results shown in the table below indicate that pitchers headed for Tommy John surgery in the near future threw slightly more fastballs and sliders than the league average peer, at the expense of slightly fewer curveballs and changeups.

He then interviewed Eric Post, who pointed out additional studies that conclude that breaking pitches have no effect:

However, in a biomechanical study using 3-dimensional analysis, Dun et al. compared the elbow varus torque produced by the fastball, curveball, and change-up in a group of youth (11-14 year old) pitchers. They found that the fastball produced significantly more varus torque than the curveball and that the change-up produced significantly less varus torque than the other two pitches. Additionally, Nissen et al. analyzed high-school pitchers using 3-dimensional motion analysis and also found that the curveball produced significantly less varus torque at the elbow than the fastball.

There have also been non-biomechanical studies examining the relationship of pitch type to injury. Olsen et al. retrospectively examined a group of teenage pitchers (14-20 years old) and found no significant difference between a group that sustained an elbow injury and a non-injury group in the age the pitchers began throwing breaking balls. In a 10-year prospective study performed at the American Sports Medicine Institute by Fleisig et al., there were no significant differences found in the age of first throwing curveballs between a group of healthy youth pitchers and a group of youth pitchers who retired due to injury or had surgery.

While some people may personally disagree, the studies so far point to breaking balls not being the problem. Instead, fastballs seem to be the culprit when it come to elbow injuries. And the one main indicator of a future Tommy John surgery is a previous elbow injury.

Shoulder Health

One huge positive advancement recently has been the ability of pitchers to develop their shoulder muscles–key word: muscles. Muscles can be strengthened. One example is the Tampa Bay Rays pitching staff, as noted here:

[James Shields] devoted himself to the Rays’ shoulder-strengthening program, a 30-minute workout using bands, dumbbells and weighted balls twice a week for 30 minutes.

“No matter where I pitch,” explains David Price, the Rays current pitching ace, “I’m taking this program with me. It’s the best. I tell everybody that comes here, ‘You probably won’t be very good at these [exercises] for a year. It’s tough on your arm at first. It makes you pretty sore. But once you get acclimated to it, it’s great.’ If I didn’t do it now? I would feel it big time.”

A stronger shoulder means that the pitcher can throw harder with less stress to the area. The problem is that the ligaments in the elbow now become the weakest point. If we combine the number of elbow- and shoulder-related disabled list stints longer than 90 days from 2002 to 2011, we find that 51 percent were related to shoulder injuries, with the lowest value being 39 percent in 2004. In 2012 and 2013, however, that total dropped to just 33 percent.

While that certainly isn’t conclusive, we could be seeing a transfer of injuries from the shoulder muscles–which can be strengthened–to the elbow ligaments, which can’t. Monitoring this trend in the upcoming seasons will be a key to help explain the increase in TJS.

Help Out: Did pitchers who had TJS previously have shoulder or elbow issues first in their career before the UCL gave out? Basically, we should look to see whether or not major shoulder injuries prevented Tommy John surgeries from happening.


Having the right mechanics is one of the more useful methods of injury prevention, but there are wide swaths of differences in opinion on what “right” is. Here are some various takes.

From Jeff Bittiger, a former big league pitcher, independent league manager and pitching coach, and now a scout for the A’s:

‘But I think this is more a matter of style, the way the game is played now and the type of deliveries that are being taught.’ By that, he means, the trend is toward pitching ‘downhill,’ at the bottom of the strike zone. Which means the ‘only way to finish those pitches is straight down,’ he said. ‘And to get there, you have to be a “short-strider.”‘ Remember that old, long-striding ‘Tom Seaver drop-and-drive delivery’ that pitchers used in the 1960s, ’70s and early ’80s–while [theoretically] staying a lot healthier and pitching many more innings? ‘No one would ever teach that now.’

From Angels pitching coach Mike Butcher:

And just as importantly, Butcher says too many professional pitchers are throwing from the opposite side of the rubber (meaning, a right-hander throwing from the first-base side and a left-hander throwing from the third-base side).

Butcher has found that more than 30 of the pitchers who have undergone Tommy John surgery this year fit that description.

“Some guys do it because they feel like they’ll be in the strike zone more, they’ll have better command that way—there’s all sorts of different philosophies about it,” Butcher said. “But for me, if you’re on the opposite side of your throwing arm on the rubber, you are constantly pronating your arm at a higher rate than if you are on the other side. There’s no leverage behind the baseball.

From writer Lindsay Berra:

At the time, John was 31 years old with 124 wins and 11 seasons under his belt. He never threw heat like Strasburg, instead relying on a bottom-out sinker that forced ground balls. But the two pitchers–as well as many others who have undergone UCL reconstruction–have one thing in common: a mechanical flaw in the timing of their deliveries that causes the arm to lag behind the rest of the body, putting extra stress on the shoulder and elbow.

The one issue I have with mechanics-based injury issues is everyone has his or her own unique answer to the problem, which the above examples demonstrate. Another issue is an understandable fear and stubbornness from the pitcher and/or the team. If a pitcher has horrible mechanics, but he’s throwing 95 mph and striking out everyone on the planet, why is there any incentive to change? The pitcher and team will always take the most productive route until the pitcher can no longer physically pitch the way he previously did.

Also, what works for one pitcher and allows him to throw for years without injury may not work for another pitcher. Until some agreed-upon or majority ideas on mechanics are acknowledged, this area is really not going to move forward.

Help Out: A Google search for “correct pitching mechanics to prevent Tommy John surgery” returns over 110,000 results. A consensus needs to be established. What I would like to see done is someone poll every possible MLB pitching coach, every team head trainer and doctor, experts not related to an MLB team and every TJS recipient and ask them same set of multiple choice and/or Yes-No questions. Does throwing a slider increase Tommy John surgeries? Does a curveball? Would you tell a pitcher not to throw a breaking ball as much? Would you recommend a pitcher throw two mph slower to help prevent and injury? A set of 20 to 30 questions could really clarify what they see as fact, fiction or just don’t know.

Innings Pitched or Pitches Thrown

Quite a bit of discontent exists on what is the perfect number of pitches to prevent injury. Long gone are the games with a pitcher throwing 150 pitches for nine innings. Now it seems like teams have taken it too far the other way, with system-wide hard limits on the number of pitches a starter can throw.

The problem is, each pitcher is different and will respond differently to varying workloads. One solution is not going to work for all pitchers. Some pitchers will not be able to achieve their maximum production while others will break down with cookie-cutter limits. Teams need to know each individual pitcher, when they begin to tire, and when their mechanics begin to break down.

The focus should not be on pitches on innings. Instead, I believe the focus should be on whether or not the pitcher maintains his velocity and mechanics.

College vs. High School Pitchers

Just a couple of months ago, people could just point to this individual case or that case of a college pitcher being abused and how it led to Tommy John surgery in the majors. We can thank Baseball America’s JJ Cooper for giving everyone a baseline of information with his recent study. The highlight of his study, which you will need a BA subscription to read in full, is:

But when it comes to pitchers drafted out of four-year colleges, the numbers move in the opposite direction. While 30 percent of pro pitchers were college draftees, 39 percent of Tommy John cases came from the college ranks.

To take a deeper look, we then focused on Tommy John cases in which the pitcher’s injury happened within the first seven years of signing a pro contract. … Limited to seven years, the numbers get worse for college draftees, because college arms made up 97 of the 223 (43.5 percent) Tommy John surgeries that took place during pitchers’ first seven pro seasons.

Now we have a baseline the odds of whether a college or high school pitcher is more prone to TJS, but that is all it is–a baseline.

Help Out: While I am focusing on MLB pitchers, a bunch of studies can be done here to compare college and MLB cases and look for trends. What are the most and average pitches per game? Smallest rest period? Pitcher velocity? Can we find any parallels or distinctions between these the college and pro pitchers?

Youth (High School and Earlier) Pitching

Right now, youth pitching is taking most of the blame, and in my opinion rightfully so. There should have been zero reason for Dr. James Andrews and ASMI to come out with a position statement on youth pitcher workloads and days.

A 12-year-old throwing 100 pitches on Thursday for one team and then another 100 on Saturday is wrong. If MLB pitchers can’t do it, why should 12-year-olds? Additionally, some pitchers end up throwing 12 months out of the year. Most MLB pitchers get 3-4 months off to recover. Kids should not be expected to throw more.

Don’t believe me? How about Pirates starting pitcher Gerrit Cole, who has never had an elbow injury:

I just played (regular season), while other guys were playing fall ball, winter ball, multiple travel teams,’ Gerrit said. ‘There’s a reason grown men have an offseason. Why would you not think a 12-year-old needed that?’

Until the stupidity ends and kids have a reasonable pitching workload, youth baseball and those who promote it will continue be attacked. One problem is that those “in charge” of youth baseball don’t want to see less baseball, as their paychecks would inevitably be lighter as a result. It will need to start with parents and kids.

That’s not just angry talk, either. Russell Carleton at Baseball Prospectus recently looked at pitchers from states with pitch-count regulations and those without and came to the following conclusion:

Pitchers from un-regulated [pitch count] states were 63 percent more likely to have an elbow injury and 32 percent more likely to need Tommy John surgery in a given year than those from regulated states. The findings weren’t statistically significant for Tommy John surgery, but they were for an initial elbow injury, and that’s the no. 1 risk factor for becoming a TJ patient.

Help out: Besides unregulated pitch count states, it would be helpful to see if pitchers who had Tommy John surgery were disproportionately from warm weather states (California, Texas, Florida) where they could more easily play all year long than cold states with a limited season (Ohio, New York, Michigan).


In my current opinion, there have been three major reasons for the increase in Tommy John surgeries:

  1. Pitchers are developing their shoulders better. This leads to a pitcher’s elbow giving out before his shoulder.
  2. Pitchers are throwing at a higher velocity, which means more stress on the elbow. More stress means more of a chance for a snap or rip.
  3. Younger pitchers are putting undo stress on their arms at too early an age, with too many innings and not enough rest time. The pitchers are damaged goods before they make it to the majors.

While I current believe these to be true, more studies need to be done in order to confirm or alter my opinion. As more information becomes available, a better understanding can be made about Tommy John surgeries, and possibly some kind of solution can be crafted.

Tommy John surgeries will never go away. Instead, I hope the number eventually will stop increasing and taper off as more knowledge becomes available for the public to digest. Until then, baseball fans should understand they will continue to see their favorite pitchers go under the knife.

References & Resources

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.
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Chris O'Leary
9 years ago

With respect to the question of proper pitching mechanics, in my opinion the problem is that, while “proper pitching mechanics” used to be defined as anything that helps you throwing hard while staying healthy, in the current definition that second proviso has been dropped.

Now, in large part due to Tommy John Surgery removing the fear of injury, “proper pitching mechanics” are anything that let you throw hard.

I discuss how and why the ways that pitching (and throwing) mechanics are taught, and how that is contributing to injuries, in my new piece on the


Brian Cartwright
9 years ago
Reply to  Chris O'Leary

Jeff comments in his “innings pitched” paragraph are what I have been saying for years. Each pitcher is at least a little different, and some maybe inherently more injury prone than others – but when a pitcher is fatigued, it is quite easy for the fatigue to cause a pitcher’s mechanics to change from his normal baseline, and it’s this difference from the baseline that puts additional stress on the pitcher’s anatomy. I believe it is the coaches job to be able to detect when a pitcher is fatigued (there are many visual and performance clues) and get that pitcher out of the game, while also noting how deep the pitcher was able to go, and work on conditioning to be able to extend the time before a pitcher is fatigued.

John D.
9 years ago

Although it makes little sense at first glance I wonder if the time taken between pitches is contributing to the increased occurrences of elbow injuries? It seems the long the games get, the greater number of elbow injuries. Perhaps too much rest between pitches allows the player to throw at 100% almost all the time?

Mike Green
9 years ago

This is a fine article. Jeff hints at something that I thought should be made explicit. Studying the reasons for the increased number of TJS over time is complicated by the growing sophistication of the surgery and shorter rehab times after it. We do not know how many pitchers had partially torn UCLs in the past and simply spent time on the DL with an unspecified elbow injury and then continued. Pitchers are much more inclined to go under the knife now.

Jeff Zimmerman
9 years ago

A link I want to add for reference where Rick Honeycutt and Nolan Ryan want to lower the mound to prevent TJS:


Also mentions Ryan threw with a torn UCL for 6 seasons.