When Jacob deGrom debuted with the New York Mets in 2014, he looked like a typical late-blooming college arm – a lanky six-foot-four right-hander with a live fastball but no guarantee of stardom. What followed was one of the most remarkable velocity arcs in modern pitching history. Over the next decade, his fastball did not follow the traditional aging curve; instead, it peaked during his two Cy Young seasons and then adjusted in the face of repeated injuries. Understanding the evolution of deGrom's fastball velocity requires looking beyond the box score – it's a story of biomechanical refinement, training innovation, and the brutal toll of elite pitching.

The Unlikely Path to Stardom

DeGrom's rise to prominence was anything but conventional. Selected in the ninth round of the 2010 MLB Draft out of Stetson University, he was considered a projectable arm with a mid-90s ceiling. His minor league career was unremarkable by velocity standards: he sat in the low 90s and relied on command and pitchability to advance through the Mets system. When he arrived in Queens at age 26, already older than most top prospects, few projected him as a future Cy Young winner. His debut season in 2014 saw him post a 2.69 ERA over 22 starts, earning him the National League Rookie of the Year award. But his fastball velocity – an average of 93.6 mph – was solid without being spectacular.

What made deGrom's fastball effective from the very beginning was its combination of carry and command. He could elevate the pitch for swings and misses or run it in on hitters' hands. His release point was consistent, and his extension down the mound gave his fastball the illusion of being faster than it actually was. According to Statcast data, his perceived velocity was often 1–2 mph higher than the raw reading because of his 6.5-foot release extension. That early advantage laid the groundwork for everything that followed.

By 2015, deGrom's average velocity had ticked up to 94.5 mph, and he was already touching 97 mph in key spots. In his Rookie of the Year campaign, he used his fastball roughly 58% of the time, generating a whiff rate above 10% – solid but not elite. His success came from locating the fastball to both sides of the plate and setting up his devastating slider and changeup. Even as his velocity gradually increased, his command remained his primary calling card. A look at his 2016 season shows an average fastball velocity of 95.2 mph – a full 1.6 mph higher than his debut year. That uptick coincided with improved strength and a more consistent release point honed during the offseason. He also added a curveball to his repertoire, giving hitters another pitch to respect and making his fastball even more effective when he did throw it.

The Biomechanical Breakthrough: 2017–2019

The 2017 season marked a turning point in deGrom's career. His average fastball velocity jumped to 96.0 mph, and he began routinely touching 99 mph in the middle innings. For the first time, he was one of the hardest throwers in the National League. But the real velocity peak arrived in 2018, the year he won his first Cy Young Award. That season, deGrom averaged a blistering 96.9 mph on his four-seam fastball and threw 99+ mph on over 400 pitches. He also posted a career-best 11.6 K/9 rate, driven largely by his fastball's effectiveness. His slider became nearly unhittable when paired with a 97-mph fastball, and his changeup – a pitch he had developed in the minors – became a lethal third weapon.

Why the jump? Biomechanical analysis from MLB.com's David Adler showed that deGrom had refined his hip-shoulder separation and improved his stride length. He was getting more extension down the mound, which made his already fast fastball play up even more. In 2019, his second Cy Young season, the average velocity was essentially identical – 96.8 mph – and his ability to sustain 97–98 mph deep into games became legendary. He threw more than 200 innings in 2018 and 2019 combined, and his velocity rarely dipped below 95 mph even in the seventh or eighth inning. That stretch was the apex of his fastball's physical dominance.

It's worth noting that during this period, deGrom also began throwing his fastball less frequently, dropping its usage to around 45% of his pitches. He relied more on his slider and changeup, which became even more effective when batters had to respect a 98-mph fastball with high spin. The result was back-to-back Cy Youngs and an ERA below 2.00 across those two seasons. His 2018 season, in particular, was historic: a 1.70 ERA with 269 strikeouts in 217 innings, all while pitching for a Mets team that scored just 3.4 runs per game in his starts. His fastball was the engine of that dominance, and it was running at peak efficiency.

Drilling deeper into the 2018 season, deGrom's fastball spin rate averaged 2,450 RPM, which placed him in the top 10% of all pitchers. That spin, combined with his extension and velocity, created a pitch that had both high perceived speed and significant rise. Hitters consistently swung under the pitch, producing a whiff rate of over 14% – elite by any standard. He also showed remarkable consistency: in 31 of his 32 starts that season, his average fastball velocity was within 0.5 mph of his season average. That level of repeatability is rare and spoke to his mechanical discipline and physical preparation.

The Injury Era and Velocity Adjustments: 2020–2022

Like many elite pitchers, deGrom's career trajectory intersected with injury. The 2020 season, shortened to 60 games by the pandemic, saw him pitch just 68 innings, but his velocity remained around 96 mph. The underlying concerns were already present: he missed time with a lat strain and began experiencing forearm tightness. In 2021, he made only 15 starts before succumbing to a right elbow injury that eventually led to Tommy John surgery. That season, his four-seam fastball averaged 96.1 mph – still elite, but down about 0.5 mph from his peak. More importantly, his whiff rate on the pitch dropped from the mid-14% range to 11.7%, suggesting that hitters were beginning to catch up.

The 2021 season was a microcosm of deGrom's career at that point: flashes of brilliance followed by breakdown. In his first seven starts, he posted a 0.68 ERA with 81 strikeouts in 46 innings, and his fastball was touching 100 mph with regularity. But his body could not sustain that level of output. The forearm tightness that cropped up in June was a warning sign that went unheeded until the elbow gave out in July. After missing most of 2022 while recovering from surgery, deGrom returned with the Texas Rangers in 2023. In his spring training outings that year, he was sitting at 96–97 mph, occasionally touching 99 mph. However, he lasted only six starts before a new injury – right elbow inflammation – ended his season. The limited data from 2023 shows an average fastball velocity of 95.8 mph. While that is down from his Cy Young peak, it remains above the major-league average for a starting pitcher.

The real question is not just the velocity number but whether deGrom can sustain it over a full season and maintain the command that made his fastball so devastating. In his six starts with Texas, his fastball command was noticeably worse than in his prime: he missed arm-side more frequently and left the pitch in the middle of the zone more often. That likely contributed to his 2.67 ERA being respectable rather than dominant. When your fastball is 98 mph with elite command, you can miss barrels. At 96 mph with average command, the same pitch becomes hittable.

Factors Behind the Velocity Evolution

Physical Conditioning and Training

DeGrom has long been known for his rigorous off-season training, which focuses on explosive leg drive and rotational power. As he matured, he added lean muscle mass without sacrificing flexibility. His training data, chronicled by FanGraphs, indicates that his peak velocity coincided with peak lower-body strength measured by vertical jump and med ball toss metrics. When injuries disrupted his routine, his velocity declined not just because of arm issues but also because his leg strength and delivery mechanics became less consistent. His offseason program in 2018 and 2019 included weighted ball training, plyometric lunges, and rotational medicine ball throws – all designed to maximize hip and shoulder torque. That program worked spectacularly, but it also placed immense stress on his elbow and forearm.

Mechanical Adjustments

Biomechanical analysis from Driveline Baseball and other groups has shown that deGrom made subtle changes to his stride and arm slot around 2017. He increased his hip-to-shoulder separation (the "X-factor") and began landing more closed, which allowed him to generate more torque. This mechanical change directly contributed to the velocity jump. Conversely, after his forearm and elbow injuries, he struggled to replicate that exact movement pattern, leading to a slight deceleration. His arm slot dropped from a high three-quarters to a more sidearm position in some outings, which reduced his extension and changed the movement profile of his fastball. The pitch lost some of its induced vertical break, making it flatter and easier for hitters to track.

Age and Natural Decline

DeGrom turned 36 in June 2024. For most pitchers, fastball velocity peaks between ages 24 and 28, then begins a gradual decline. DeGrom's peak was later than average – around age 31, which is highly unusual. Since 2019, his velocity has dropped roughly 1 mph per year on average, which aligns with the expected aging curve for hard-throwing pitchers. The key factor is that his decline has been expedited by multiple serious injuries, not just Father Time. If we project a normal aging curve for a pitcher who throws as hard as deGrom did, he would be expected to lose about 0.3 to 0.5 mph per year after age 30. His actual decline has been steeper because of the Tommy John surgery and subsequent complications.

Injury History and Management

No discussion of deGrom's velocity evolution is complete without examining his injury history. He suffered a torn ulnar collateral ligament in his right elbow after the 2021 season, followed by Tommy John surgery in June 2022. Prior to that, he had dealt with lat strains, hamstring issues, and forearm tightness. Each time an injury forced him to alter his delivery, his fastball command suffered, even if the raw velocity remained high. The 2023 season saw him attempt a comeback but ultimately break down again. The Rangers and their medical staff have been cautious, but the data suggests that his fastball, while still elite when healthy, has lost about 1.5 mph from its peak and is more susceptible to location mistakes.

The relationship between injury and velocity is complex. Many pitchers lose velocity immediately after returning from Tommy John surgery because they are still building arm strength and trust in their mechanics. DeGrom was actually ahead of schedule in 2023, touching 99 mph in spring training. But the subsequent inflammation suggested that his elbow could not handle the stress of high-velocity pitching over a full season. This raises the question of whether deGrom can ever return to his peak velocity without risking further injury. The answer, based on historical precedent, is likely no. Pitchers who undergo Tommy John surgery after age 30 rarely regain their pre-injury velocity. DeGrom was 34 when he had the surgery, making a full velocity restoration highly unlikely.

Comparative Context: Where Does deGrom's Fastball Stand?

For context, among starting pitchers with at least 500 innings since 2014, deGrom's average fastball velocity over his career ranks in the top 5%, alongside names like Gerrit Cole and Noah Syndergaard. At his peak in 2018–2019, his average four-seam velocity of 96.9 mph was the second-highest among all MLB starters, trailing only Syndergaard. Even with the decline, his 2023 average of 95.8 mph would still rank among the top 15 starters in the league today. However, the gap between his fastball and the league average has narrowed: in 2018, he was 4.2 mph higher than the average starter; by 2023, that gap shrank to about 3.1 mph. That reduction matters because hitters have become more accustomed to high velocity and can better adjust when the pitch loses a tick.

A useful comparison is Max Scherzer, who also experienced a late-career velocity drop but compensated with elite pitch sequencing and command. Scherzer's average fastball velocity peaked at 96.0 mph in 2016 and declined to 93.5 mph by 2023. Yet he remained an effective pitcher because he adjusted his approach: he threw more cutters and changeups, and he located his fastball with surgical precision. DeGrom's command has historically been elite, but his fastball missed more barrels when it was 98 mph than when it is 96. The difference in raw force, measured in terms of the time the ball takes to reach the plate, is about 0.01 seconds – small but meaningful at the highest level.

Another comparison is Justin Verlander, who underwent Tommy John surgery at age 35 and returned to throw 98 mph in his late 30s. Verlander's recovery was exceptional, and it offers some hope for deGrom. But Verlander is an outlier. Most pitchers do not come back from a major elbow surgery at deGrom's age and regain elite velocity. Verlander also benefited from a cleaner recovery and a body that responded better to the rehab process. DeGrom's history of multiple injuries – lat, hamstring, forearm, elbow – suggests a more fragile physiology that may not hold up under the same workload.

The Role of Technology in the Velocity Evolution

The velocity evolution of Jacob deGrom also reflects broader trends in baseball technology. When deGrom debuted in 2014, Statcast had just been installed in all 30 ballparks. By 2018, teams were using high-speed cameras to analyze every aspect of a pitcher's delivery. DeGrom and the Mets used this data to identify the mechanical changes that unlocked his velocity jump. Driveline Baseball, a training facility that specializes in biomechanics, worked with deGrom in the 2017 offseason to refine his hip-shoulder separation and maximize his kinetic chain efficiency.

The impact of technology on deGrom's career should not be underestimated. Without the ability to measure his spin rate, extension, and release point in real time, it is unlikely that he would have made the mechanical adjustments that led to his velocity peak. Teams like the Mets invested heavily in these technologies, and deGrom was an ideal candidate to benefit from them: he was already a good pitcher, but the data showed him that he could be great. The alignment of timing, technology, and talent created the perfect conditions for his velocity surge.

Since his injuries, deGrom has continued to use technology to guide his rehab. The Rangers employ a robust biomechanics program that tracks every throw he makes, looking for deviations in his delivery that could signal impending injury. This data-driven approach has helped him manage his workload and avoid further setbacks. But it also shows that his current velocity ceiling is likely lower than it was before the injuries. The technology can help him optimize what he has left, but it cannot reverse the physical damage.

The 2024 Season and Beyond: What Remains of the Fastball

As of the 2024 season, deGrom has not thrown a competitive pitch since April 2023. He is working his way back from a second elbow surgery – a repair of the internal brace procedure – and is expected to return sometime in mid-to-late 2024. Reports from his throwing sessions in March 2024 indicated that his fastball was sitting at 93–95 mph, with the occasional 96. That would represent another small step down. Whether he can regain the 96–97 mph range that made him a Cy Young candidate depends on how well his body holds up and whether he can rebuild the leg strength that drove his peak velocity.

Even if his fastball settles at 94–95 mph, deGrom still possesses above-average spin (averaging 2,450 RPM on his four-seamer) and elite extension. That combination will keep him viable, but it may no longer be the overpowering pitch that defined his prime. To remain effective, he will need to lean even more heavily on his secondary pitches. His slider remains one of the best in baseball when healthy, and his changeup has consistently been above average. If he can pair a 95-mph fastball with elite command and two plus secondary pitches, he can still be an above-average starter. But the days of dominating solely with velocity are likely behind him.

The evolution of Jacob deGrom's fastball velocity is a case study in what happens when extraordinary talent meets the relentless demands of high-level pitching: a peak that defied aging, followed by a decline accelerated by physical breakdowns. For fans and analysts, the numbers tell a story of a pitcher who redefined what a starting pitcher's fastball could do – and then had to learn, painfully, that no velocity is immune to time or injury. Whether he can reinvent himself with a slightly slower but still elite fastball remains one of the most compelling narratives of the 2024 season.

The broader lesson from deGrom's career is that velocity, while critical, is not everything. His peak coincided with perfect mechanical efficiency and optimal training, but that state could not be sustained indefinitely. Pitchers who rely on velocity as their primary weapon face a constant battle against the forces of aging, injury, and adaptation by hitters. DeGrom's ability to win two Cy Young awards despite not having the highest velocity in the league for most of his early career demonstrates that pitchability, command, and secondary stuff can compensate for modest velocity. As he enters the final stages of his career, those skills will be more important than ever.

For the Texas Rangers, the investment in deGrom was a calculated risk. They knew that his injury history made a full season unlikely, but they were willing to bet that even a partial season of elite pitching could help them win a championship. That bet did not pay off in 2023, but deGrom could still contribute in 2024 and beyond if his arm holds up. The velocity numbers will tell part of the story, but the true measure of his success will be his ability to pitch deep into games and help his team win – regardless of whether his fastball sits at 95 or 97 mph.