Is Velocity Really The Culprit Behind Rising Baseball Injuries?

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Dr. Nick Serio is the founder and president of VeloU, a baseball performance and pitching development company focused on improving velocity, mechanics, strength and arm health through data-driven instruction.

In late 2024, Major League Baseball released a comprehensive report that formalized what everyone in the game already knew: Pitcher injuries aren’t just increasing—they’re accelerating. The data tells a story that’s impossible to ignore.

Ulnar collateral ligament (UCL) reconstruction surgeries in the major leagues jumped from 21 in 2010 to 46 in 2024. Minor league numbers paint an even bleaker picture, as procedures surged from 83 in 2010 to 240 in 2024. Days lost to injury have climbed steadily since 2005. The report interviewed more than 200 experts across orthopedic surgery, biomechanics, athletic training and front office representatives. The conclusion was unanimous: We have an epidemic on our hands.

But here’s what makes the situation even more concerning. Baseball has responded exactly as you’d expect an evidence-based industry to respond. Organizations have shortened pitcher outings, reduced total innings workloads and even increased the number of pitchers they carry to spread the burden across more arms. Every intervention has been designed with the goal of reducing the physical stress on pitchers’ arms.

And yet, the injury rates keep climbing.

Something isn’t adding up. If the protective measures address the root cause, they should work. The fact that they haven’t suggests we might be treating a symptom rather than the disease itself.

The Consensus View On Velocity

So, what does the baseball community think is causing all of this? Ask anyone in the game, and you’ll hear remarkable consistency—velocity is the problem. It’s the pursuit of elite stuff and max-effort pitching on every single throw. Athletes are throwing harder than ever before, and it seems as though their bodies simply can’t sustain the stress.

The MLB report’s interviews reflect exactly this. Expert after expert pointed to velocity as the primary culprit.

“If you could take one factor, it’s velocity,” one orthopedic surgeon stated. Another called it “the biggest problem.” A pitching development coach described max-effort throwing as “the number one factor in UCL injuries.” Former pitchers described the shift from throwing at 20% maximum effort in their era to modern-day pitchers operating at 100% constant intensity.

The evidence supporting this view seems straightforward. Average fastball velocity in the major leagues has increased from 91.3 mph in 2008 to 94.2 mph in 2024. At the same time, injury rates have surged. The correlation appears clear.

And what makes this particularly concerning is how successfully this velocity-first approach has permeated the entire player development pipeline. College pitchers are chasing velocity to get drafted. High school athletes are maxing out to get recruited. Showcase culture has created an arms race in which radar gun readings determine opportunity. The same patterns driving professional injuries now exist at every level of amateur baseball.

The logical conclusion seems obvious. If velocity is destroying professional arms and the amateur game has adopted the same velocity-obsessed approach, we’re creating a generational problem that will only compound over time.

But what if we have the direction of causation backwards?

What If The Water Flows Upstream?

Here’s a different way to look at the same data. What if the professional injury epidemic isn’t being caused by what happens at the major league level? What if it’s the inevitable result of what it took to get there?

Think about the path a pitcher takes to reach professional baseball. High school showcases where velocity determines who gets noticed. College recruitment where radar gun readings open or close doors. The draft process, where stuff and velocity projections drive selection. At every stage, the athlete who throws harder advances. The one who doesn’t gets left behind.

This isn’t speculation. The data shows exactly how the game has changed at the amateur level. In 2014, five high school pitchers threw 95 mph or harder at Perfect Game’s National Showcase. By 2024, that number had reached 36. That’s not a gradual trend—it’s a fundamental transformation of what we consider normal velocity for amateur athletes.

So, maybe the question isn’t why are professional pitchers getting injured at higher rates. Maybe it’s why wouldn’t they be getting injured, given what their bodies had to endure to earn the opportunity to pitch professionally in the first place?

The Damage Done Before They Arrive

Research tracking thousands of pitchers reveals something that changes the entire framework of how we should think about this problem: 54% of all UCL injuries occur in athletes aged 15 to 19. Not in the major leagues, not even in college. In high school.

A survey of 214 professional and amateur pitchers found an even more striking pattern. Of the pitchers who had suffered UCL injuries during their professional careers, 55% had a history of elbow injuries as adolescents or children. In the group that never injured their UCL at the professional level? Only 18% had childhood elbow issues.

Let that pattern sink in. More than half of the pitchers who eventually need surgery as professionals already had elbow problems as kids. The statistical significance of this study is downright overwhelming. This can certainly be viewed as a predictive relationship.

Furthering this point, the consequences of early injury appear to extend far beyond recurrence risk. A study of 611 first-round draft picks found that only 48.1% of pitchers who underwent UCL reconstruction at or before roughly 19.5 years of age reached MLB, compared to 86.2% of those who had surgery later in their careers. It’s the same procedure and the same rehabilitation protocols, but if it occurs before age 20, the odds of reaching the goal are cut in half.

For every additional year a pitcher avoided injury after first hitting 90 mph, their odds of making the big leagues increased by 24%. Even for those who did eventually reach the majors, early surgery resulted in careers that were 1.5 seasons shorter on average.

The professional injury epidemic isn’t just happening at the professional level. It’s being created years earlier, during the exact developmental window when athletes are chasing velocity to get recruited.

The Biological Reality Of Adolescent Development

Why are injuries concentrated so heavily in the 15 to 19 age range? The answer lies in basic human biology that has nothing to do with baseball.

Research tracking youth athletes across multiple sports has identified the period surrounding peak height velocity as maximum injury vulnerability. This is when adolescents are growing fastest, typically between ages 13 and 17 in baseball. Studies found injury risk spiking 31% to 53% in the six months following an athlete’s growth spurt. Athletes growing faster than approximately three inches per year face 74% higher injury risk, regardless of what sport they play.

What, then, is the mechanism that causes this time period to be so risky? During the later part or just after peak height velocity, an athlete’s skeletal growth is outpacing their soft tissues’ ability to adapt. Essentially, the athlete’s bones are lengthening faster than their tendons and ligaments can remodel, creating a structural mismatch. To bring this context back to baseball, imagine a pitcher’s arm is literally longer this month than last month, but the ligaments stabilizing his elbow haven’t caught up. As such, the leverage has changed, which means stress will be experienced very differently. More simply put, the athlete’s body is solving a new physics problem with yesterday’s solutions.

Movement patterns break down during this period. Researchers document what they call “adolescent awkwardness,” where neuromuscular control becomes temporarily impaired as athletes must relearn motor patterns in bodies that have changed seemingly overnight. Proprioception falters. The pitcher who had command one month loses it the next, not from mechanics regression, but from biology. His brain is still sending signals calibrated for his old body, but he’s pitching with a new one.

After just 35 pitches, 56% of adolescent pitchers showed more than 20% strength loss in their finger flexors. Hip strength dropped. Rotational coordination degraded. These weren’t professional pitchers throwing 100-pitch outings. These were kids barely halfway through what we’d consider a normal start, and their systems were already breaking down.

This creates an impossible situation. The period of maximum biological vulnerability, when tissues are most susceptible to damage from high-stress activities, coincides exactly with the period when baseball demands athletes produce elite velocity to get recruited. We’re asking immature tissues to handle loads they’re not biologically ready for, during a developmental window when adaptation capacity is already compromised by rapid growth.

And once that damage occurs, the evidence suggests it may never fully resolve. Early tissue stress creates structural weaknesses that compound over years. The remodeling never quite catches up. When you layer adult velocity demands on top of adolescent damage, something eventually gives.

How Do We Know This Is The Real Issue?

If the argument is that professional injuries are actually the result of youth damage rather than professional-level velocity demands, the evidence needs to support that distinction. It does.

A systematic review tracked 2,896 pitchers across high school, college and professional levels and found something remarkable. In high school pitchers, velocity showed a moderate correlation with elbow varus torque, indicated by an R-squared value of 0.36. As those athletes matured and moved through college, that correlation weakened to 0.29. By the time they reached professional baseball, the players throwing the hardest and operating at the highest velocities the game has ever seen showed an R-squared of just 0.076.

That’s not a gradual decline. That’s a complete restructuring of how velocity relates to injury risk. The relationship that exists in high school largely disappears by the time athletes reach biological maturity.

The biomechanical research supports this pattern. When you look at high school pitchers throwing harder, they produce the highest elbow torque relative to their body size. But professional pitchers throwing even harder show similar or lower normalized elbow torque. What’s the difference? Professionals use trunk and pelvis rotation to offload stress from the elbow. Their kinetic chains have matured. Their movement patterns have stabilized post-growth. Their tissues have adapted to their adult frames.

Now, there’s certainly some survivorship bias here. The athletes who made it to professional baseball are, by definition, the ones whose bodies could handle the developmental journey. The ones who broke down at 16 never got the chance to pitch professionally. But that’s almost the point. The fact that professional pitchers show a weak correlation between velocity and injury while high school pitchers show moderate correlation suggests the vulnerability window is during development, not after it.

And that 55% of injured professional pitchers having childhood elbow issues compared to just 18% of uninjured professionals? That’s not survivorship bias. That’s a clear signal that early damage predicts future injury, even among the elite athletes who made it through the selection filter.

Potential Pathways Forward

If the real driver of professional injuries is what happens during adolescent development, then the solutions need to address that developmental window. Two potential approaches deserve consideration.

The first involves restructuring how we think about college eligibility and development timelines. Currently, junior college playing time counts against NCAA eligibility, creating pressure for athletes to progress quickly through the system. What if junior college years didn’t count toward eligibility limits? This would create a viable developmental pathway for athletes who need more time to mature physically before facing Division I workloads.

Here’s how this would help. Late-maturing athletes could develop velocity gradually, on timelines that match their biological readiness rather than arbitrary recruiting calendars. Athletes wouldn’t need to max out their arms at 16 to earn opportunities. They could develop at 18 or 19 and still have a full college career ahead of them. The pressure to produce elite velocity during the peak height velocity window would decrease significantly.

The second approach borrows from a practice that’s gained significant traction in elite European soccer academies. Bio-banding groups athletes by biological maturity rather than chronological age. Roughly two-thirds of leading European academies now use this approach, endorsed by both FIFA and the English Premier League.

What problem does this solve? A 15-year-old who hit his growth spurt at 13 is biologically years ahead of a 15-year-old who won’t hit peak height velocity until 16. They’re the same age on paper, but their bodies are in completely different developmental places. Traditional age-group competition forces them to compete for the same opportunities, which means the late maturer needs to produce outputs his body isn’t ready for or risk getting cut.

Bio-banding doesn’t replace age-group competition—it supplements it. Athletes still compete with their age peers in games and tournaments. But development work, training intensity and physical demands are matched to biological readiness rather than chronological age. How? By tracking growth velocity. Flagging athletes growing faster than approximately three inches per year for modified training loads. Identifying when athletes hit peak height velocity and recognize the six months following as maximum vulnerability. Building physical preparation before velocity demands, not after injuries force the issue.

This allows late-maturing athletes to develop technical skills and movement quality without chasing velocity their tissues can’t support. It challenges early-maturers to develop skill and efficiency rather than relying on temporary size advantages. Most importantly, it removes the pressure to produce elite velocity during the exact developmental window when tissue adaptation is most compromised.

Would either of these solutions completely solve the injury epidemic? Probably not. The problem is complex and multifactorial. But if 54% of injuries are happening between ages 15 and 19, and 55% of injured professionals had childhood elbow issues, any real solution has to address what’s happening during adolescent development.

A Different Lens

The baseball community has focused intensely on velocity as the primary driver of the injury epidemic. The evidence supporting that focus seems clear. Velocity has increased, and injuries have increased. The correlation is obvious.

But correlation doesn’t always point in the direction we assume. The professional injury epidemic might not be solely or even primarily caused by professional-level velocity demands. It might be the inevitable result of what adolescent bodies had to endure to create professional-level athletes in the first place.

The biological vulnerability window sits right on top of the recruitment and development timeline. Peak height velocity typically occurs between ages 13 and 17. Tissue adaptation is compromised, movement patterns are unstable and strength hasn’t caught up to rapidly changing leverage. And during this exact period, baseball asks athletes to produce elite velocity to earn opportunities.

Seventy percent of all ulnar collateral ligament injuries happen before age 20. More than half of injured professionals had elbow problems as kids. Surgery before age 20 cuts MLB odds in half compared to identical surgery performed later. Every year of injury-free development after first r eaching meaningful velocity improves professional prospects by nearly a quarter.

The pattern isn’t subtle. It’s screaming at us. But we’ve been looking at it through the wrong lens.

Maybe the question isn’t how do we protect professional pitchers from velocity. Maybe it’s how do we protect developing athletes during the biological window when their tissues can’t handle the velocity demands that baseball’s recruitment and advancement systems require.

That’s not just a different answer. That’s a different question entirely.

References

[1] Major League Baseball. (2024). Report on pitcher injuries. Major League Baseball.

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[7] Luera, M. J., Dowling, B., Magrini, M. A., Muddle, T. W., Colquhoun, R. J., & Jenkins, N. D. (2018). Role of rotational kinematics in minimizing elbow varus torques for professional versus high school pitchers. Orthopaedic Journal of Sports Medicine, 6(3), 2325967118760780. https://doi.org/10.1177/2325967118760780

[8] Johnson, A. L., Kokott, W., Dziuk, C., & Cross, J. A. (2025). Assessment of muscular fatigue on hip and torso biomechanics in adolescent baseball pitchers. Journal of Strength and Conditioning Research, 39(8), 893-899. https://doi.org/10.1519/JSC.0000000000005136

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