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There’s a Science Behind More High-Velocity Pitches, But There’s Also a Cost

With athletes becoming stronger and better trained, the rise in pitching velocity began as a gradual evolution. But there has been a stunning leap forward in the past four years. Here’s why.

When Aroldis Chapman began warming up in the bullpen for his first major league appearance in 2010, fans in the outfield seats at Great American Ball Park stormed the area around the Reds’ bullpen just to get a glimpse of what a 100-mph fastball looked like.

The novelty of triple digits is long gone.

It is an everyday occurrence. Not a day has gone by this season without someone throwing 100 mph.

One-hundred-mph fastballs are more common than stolen bases and double plays. Twenty-seven pitchers hit 100 mph in April, as many as pitchers did over the entire season 10 years ago.

The rise in velocity began as a gradual evolution. Athletes have grown bigger and stronger, and are better trained. But there has been a stunning leap forward in the past four years. It happened as the science of throwing became big business, fueled by biomechanics, technology and investments by private companies and major league teams.

The number of major league pitches clocked at 100 mph and faster more than tripled over three years, from 1,056 in 2019 to 3,348 last year. The rate continues to go up this season, as shown by this recent spike that includes the prorated total for ’23:


Not coincidentally, as velocity goes up, so do injuries. Teams paid $486 million last year to 427 pitchers on the injured list, a rate of $2.67 million each day. Pitchers too hurt to pitch spent 30,728 days on the IL while collecting 9% of all money paid to players. Despite better training and lighter workloads, pitchers have about the same chance of staying off the IL as a flip of a coin. Only 51% of pitchers who appeared in a game last season stayed off the IL.

This season, 173 pitchers ended April on the IL, having collected $100 million while unable to pitch, or $3.1 million per day. Five of the seven most expensive pitchers, as ranked by average annual value, began May unable to pitch: Max Scherzer, who was serving a 10-game suspension for violating the rule against sticky substances; Justin Verlander; Jacob deGrom; Stephen Strasburg; and Carlos Rodón, all of whom were hurt. (The highest-paid pitchers still taking their starts were Shohei Ohtani and Gerrit Cole.)

“We really improved the mechanics or biomechanics of many pitchers from major leagues down to little leagues,” says Glenn Fleisig, the research director at the American Sports Medicine Institute in Birmingham who is also an adviser to MLB and an established leader in pitching biomechanics.

Fleisig was a guest on my podcast with World Series–winning manager Joe Maddon, The Book of Joe. “Improving the mechanics means getting more velocity and maximizing your force of using your whole body, but that has come with a price,” Fleisig says. “It’s been a price that pitchers could pitch faster than ever before, but they’re putting more force on their elbow and shoulder than before.

“So, through optimizing mechanics and conditioning and nutrition, baseball pitchers are pushing their body to the maximum performance now and kind of redlining it and getting that maximum performance—but always teetering on the edge of overuse injury.”

When it comes to velocity, both supply and demand have increased. Teams survive the injury rate of pitchers because someone else is coming out of a pitching lab right behind them throwing 100 mph, often somewhat anonymously, rather than with the pedigree of Chapman. As this chart shows, pitchers who can throw 100 have doubled since 2019 and tripled since ’18.


On April 22, Gregory Santos threw the fastest and second-fastest pitches recorded by a White Sox pitcher, 102.3 mph and 103.1 mph—five months after he was designated for assignment. Who is Gregory Santos? In 2015, the Red Sox signed him as a 16-year-old out of the Dominican Republic with a $275,000 bonus. He was throwing 93 mph two years later, when they traded him to the Giants. In 2021, his fastball averaged 97.7. He was suspended that year for testing positive for a steroid. In ’22, he averaged 98.8. The Giants designated him for assignment in December before trading him to the White Sox.

“Maximizing velocity, it is not the pitcher who wins,” Fleisig says. “It is the team who wins. It is not the pitcher. We’ve done biomechanical studies looking at the relationship between velocity and the torque on your elbow. We found that the torque on the elbow varied a lot from pitcher to pitcher, but within any pitcher, the more velocity they throw with, the more torque on the elbow.

“Our studies have shown that to succeed, particularly as a starting pitcher, you should vary your velocities. You shouldn’t max-effort every pitch. You should mess around with the batters at various speeds of your pitches, your locations, et cetera, to succeed as a pitcher, not as a thrower. To be healthy and successful, the pitcher should vary the velocity.”

Teams always have coveted velocity. What has quickly changed the market is the ability to add or find velocity at an extreme level. Clubs consider velocity a skill that can be improved, and more and more pitchers are testing the limit of what their shoulders can withstand. The rotation of the shoulder when throwing a baseball is the fastest human motion ever measured biomechanically. The shoulder fires 7,000 degrees per second. It’s the equivalent of having your arm complete 20 circles in one second.

“It’s unbelievable,” Fleisig says.

Researchers at ASMI wondered how much more speed the human shoulder could withstand. They did research on cadavers. They found the forces the cadavers could withstand before the joint broke apart were less than the forces they measured when pitchers threw in their lab.

“So, our science says that an arm should break every single pitch, but obviously it doesn’t,” he says. “But what happens is the cadavers aren’t ... um, not to be too gross, but they weren’t young healthy men. They were older people. So the point is the elbow and shoulder are pushed to their biomechanical limit pretty much every pitch.

“But the problem is, as pitchers get faster and faster, they are getting stronger and stronger with their muscles and their mechanics are getting more finely tuned. The weak links are the ligaments and tendons. They have ligaments and tendons holding their joints together, like the Tommy John ligament in the elbow and their rotator cuff tendons in the shoulder.

“And when people work out, get stronger, essentially their muscles get stronger, but it’s really hard to strengthen your ligaments and tendons. So, what we’ve got is a situation now where, through good mechanics and good strength conditioning, the muscles and the mechanics are overpowering the ligaments and tendons.”

Here’s another chart that shows how the slow growth of velocity has suddenly spiked since 2020:


What I find fascinating are the mechanical changes pitchers are making to help push that average higher. Since 2015, the average four-seamer is being thrown with a slightly lower release point (5.86 to 5.83 feet; it was even higher in 2008) and more extension (from 6.2 to 6.5 feet). Translation: Pitchers are using their lower half more and “getting down the mound” more, rather than the old-school way of “tall and fall” and “getting your arm up.”

Fifteen to 20 years ago, teams would send pitching prospects to the ASMI lab to undergo a biomechanical evaluation. Teams weren’t sure what to do with it. Now they can get the data and crunch it themselves, even through markerless motion capture during games.

“What’s happened over the last 10 years is there’s been a revolution,” Fleisig says. “Teams are trying for a competitive advantage and are using biomechanics. I was once the only show in town, but now teams are hiring biomechanists. More than two-thirds of teams employ biomechanists, and teams have biomechanics equipment.”

How high can the maximum velocity go?

“If you asked me 10 years ago,” Fleisig says, “when Chapman or whoever was the fastest pitcher, I said in several interviews that I don’t think the maximum velocity is really going to go far up, but I think it’s going to be a glass ceiling that’s going to get more crowded near the top.

“And over the past 10 years that’s happened. The max-velocity guy might be one mile per hour faster than it was 10 years ago. But it’s really crowded. Every team has 95-plus. Pitchers now, everyone is pushing their body to the limit, but I don’t think the limit could go up, because I don’t think the ligaments and tendons can go farther.”

It may seem counterintuitive, but as pitchers throw faster, they throw fewer fastballs. The use of fastballs (not including cutters) was as high as 58.4% in 2009. Last season, it fell below 50% for the first time, to 48.5%. This year, it is down further, to 46.9%. At this rate, hitters will see 80,886 fewer fastballs than they did 14 years ago, even though the average velocity of those fastballs has gone up 1.9 mph.

But what biomechanics have done for velocity, technology has done even more for spin. Breaking pitches have become so nasty that, this year, a run-of-the-mill slider is tougher to hit (.218) than a fastball at 99 mph and above (.232). For example, St. Louis righthander Jordan Hicks has thrown the most 100-mph pitches this year (110). Hicks hit 100 mph more times in April than the entire league did in April just five years ago (92 in 2018). And yet, batters hit .333 against his triple-digit fastballs.

In this super-velocity era, pitchers also are throwing fewer pitches and with more days of rest. Ten years ago, pitchers made 51% of starts on four days of rest. By last season it had dropped to 39%. This year it is 24%. Having a rotation work every fifth day is a dead concept.

“We’re not going back to that because of the things we talked about earlier,” Fleisig says. “It’s the type of pitchers ... the maximum velocity by optimizing mechanics, getting the maximum force on the arm. So we’re going to have to deal with the fact that this is where we’re at, but there’s a balance for how hard you could push.

“There’s workload, which is the accumulation of how much force or how many pitches you throw, but there’s also a new thing. Scientists call it the acute-to-chronic workload ratio, which means not just how much have you done, but how much has it varied over the course of the days, the weeks, most of the year. And what we found in science, baseball, soccer and all sorts of sports is that athletes get hurt when they have too much workload, but also when they’re acute-chronic workload ratio is too high, meaning they’re varying up and down.”

New York Yankees' Gerrit Cole pitches in the first inning of Game 4 of a baseball AL Division Series against the Cleveland Guardians, Sunday, Oct. 16, 2022, in Cleveland.

The Yankees have kept Cole’s pitch count within the range of 92 and 109.

Developments over the past four years have created an industry standard of pitching: max out on velocity while curbing workload. The days when I tracked teams that packed huge year-to-year innings jumps on young pitchers is over. No pitcher has thrown 120 pitches since June 28, 2022, a streak of more than 3,400 consecutive starts. Over the past three seasons, a pitcher thrown 120 pitches only eight times—as many times as Kerry Woods did in a 21-start stretch as a 21-year-old rookie in 1998. Now we have real-time biomechanical measurements and acute-to-chronic workload ratios, which is why the Yankees generally pitch Cole every sixth day and have kept his pitch count within the narrow range of 92 and 109.

For years, we’ve known the biggest risk factors for injury have been poor mechanics and fatigue.

“I’ve done a lot of science over the past 35 years,” Fleisig says, “and some studies have shown [fatigue] has a 50% effect or a 100% percent effect. We did one study where it was a 36 times effect, and it was the strongest study we’ve ever done.

“We looked at a group of high-school-aged baseball pitchers who had never had an arm problem versus high school-aged pitchers who came in for surgery. We asked them many questions like, ‘How old were you when you started throwing a curveball?’ But the one question that was basically the telltale about who ended up having surgery at the high school level was, ‘Did you routinely keep pitching after you were fatigued?’

“Essentially, if you asked someone if you keep pitching up to fatigue and they said yes, I would’ve bet you $36 to one that that guy was the one who ended up with surgery versus the guy who said no. It’s huge. So unfortunately for me, fatigue is not something that can be measured very well with computers or anything like that.

“Fatigue is a self-feeling, essentially at all levels. Pitchers should keep pitching when they’re feeling good, but when they’re fatigued, it’s time to call it a day. At the amateur level, it’s, ‘Hey, he’s my best pitcher. I’m going to keep riding this guy.’ At the pro level, it’s the other way around. They’re very cautious because they have a lot invested in these guys. At the pro level, you should certainly call it a day when it’s fatigue. Part of the problem is that, on the pro level, they’re shutting it down too soon. For some guys, they’re being overly cautious.”

Now we understand there is another risk factor to add to poor mechanics and fatigue: chasing maximum velocity. It is a known risk pitchers gladly accept, especially in deep bullpens where the work tends to be short and intense. When it comes to the “wow” factor, 102 is the new 100. Pitchers touched 102 mph more times in April (83) than over the entire 2021 season (43).

Pitching has changed significantly and quickly. It is as obvious as the LED readouts on radar guns on a nightly basis. Weighted ball training, strength training and pitching labs stocked with biomechanists are sending forth more and more pitchers who are bumping up against the limit of what is humanly possible.