Jacob deGrom has redefined pitching dominance during his tenure with the New York Mets, posting ERAs so low they border on historical anomalies. Yet even a talent as transcendent as deGrom does not exist in a vacuum. Every pitch that leaves his hand enters a carefully choreographed ballet of nine fielders, each movement affecting whether a batted ball becomes an out, a hit, or a run. The team defense behind him has played a quiet but measurable role in shaping the ERA that fans and analysts alike use to celebrate his career. Understanding how defensive quality interacts with a pitcher’s output is essential for evaluating not only deGrom’s performance but also the broader mechanics of success on the mound.

The Symbiotic Relationship Between Pitcher and Defense

A pitcher’s ERA is a deceptively simple statistic: earned runs allowed per nine innings. But “earned” is a loaded term. An outfield misjudgment that turns a fly ball into a double, an infielder’s errant throw that extends an inning, or a failed shift that allows a ground ball through a vacated hole — all of these events can lead to runs that are still charged to the pitcher as earned, even when they stem from defensive failure. Meanwhile, spectacular defensive plays can erase the consequences of a poorly located pitch, keeping the ERA artificially low. The quality of team defense thus acts as a fundamental modifier of the number that often defines a pitcher’s season.

Defense influences ERA through multiple pathways. First, there is simple error avoidance: fewer errors mean fewer unearned runs, but also fewer extended innings that wear down a pitcher and increase the likelihood of subsequent earned runs. Second, range — the ability of fielders to reach balls that an average defender would not — directly reduces batting average on balls in play (BABIP). A high-BABIP season for a pitcher can often be traced to poor defensive positioning or skill rather than the pitcher himself. Third, the psychological effect of a reliable defense allows a pitcher to work more efficiently, attacking the strike zone without the fear that a weak grounder will become a rally starter.

DeGrom’s style — heavy reliance on a four-seam fastball that generates whiffs and a slider that induces weak contact — makes him less dependent on defense than many other pitchers. His elite strikeout rate (career 28.5% as of 2024) means more than a quarter of opposing batters never put the ball in play. Yet even a pitcher like deGrom faces hundreds of balls in play each season. In his 2018 Cy Young campaign, for example, batters put 387 balls in play against him. The outcome of those 387 events — whether they became outs or hits — depended heavily on the defenders behind him.

Jacob deGrom’s Defensive Context: A Team in Flux

The Early Years (2014–2017)

When deGrom debuted in 2014, the Mets fielded a defense that ranked near the middle of the league. According to Defensive Runs Saved (DRS), the Mets fluctuated between 0 and +10 in those years, with occasional bright spots like left fielder Michael Conforto’s arm and shortstop Asdrúbal Cabrera’s steady glove. DeGrom’s ERA during that period (2.98) was solid but not yet elite, and his FIP (Fielding Independent Pitching) hovered around 2.70, suggesting that the defense was actually helping him slightly — his ERA was lower than his FIP by about 0.28 runs. This pattern indicated that the Mets’ defense was, at the time, converting balls in play into outs at a rate that benefitted deGrom.

The Peak Years (2018–2021)

From 2018 through 2021, deGrom transformed into arguably the most dominant pitcher of his generation, posting ERAs of 1.70, 2.43, 2.38, and 1.08 (in a shortened 2021 season). Yet during this same stretch, the Mets’ team defense was far from elite. In 2018, the Mets ranked 22nd in DRS (-18) and 24th in Ultimate Zone Rating (UZR). In 2019, the defense improved slightly to 14th in DRS, but by 2020–2021 it had slipped back to the bottom third. It would be reasonable to expect that poor defense would inflate a pitcher’s ERA, but deGrom’s ERA was consistently lower than his FIP during these years — his 2018 ERA of 1.70 vs. FIP of 1.99; 2019 ERA 2.43 vs. FIP 2.67; 2020 ERA 2.38 vs. FIP 2.26 (a slight reversal); 2021 ERA 1.08 vs. FIP 1.57. The gap in 2018 and 2019 suggests that even a below-average defense can still help a pitcher if the pitcher limits hard contact and induces weak ground balls that fielders can convert. Indeed, deGrom’s ground-ball rate (over 45% in 2018) and his ability to miss barrels (his barrel rate allowed was in the 99th percentile) meant that the defense faced easier chances than the average pitcher would provide.

The Decline of the Mets Defense (2022–2023)

In 2022, deGrom was limited to 11 starts due to injury, but the Mets fielded a defense that ranked 25th in DRS. When deGrom did pitch, his ERA rose to 3.08, while his FIP was 2.74. This was the first time in years that his ERA exceeded his FIP, implying that the defense was not converting balls in play as efficiently — the team’s BABIP against him was .320, well above the league average. The 2023 season saw deGrom move to the Texas Rangers, a team with a far superior defense (ranked 2nd in DRS in 2023). In his limited starts with Texas, his ERA was 2.08 and his FIP was 2.73, a reversal of the previous year’s gap. The defensive improvement in Arlington likely helped deGrom’s ERA settle below his FIP once again.

Advanced Metrics That Isolate Defensive Impact

Fielding Independent Pitching (FIP) and Its Variants

The most common way to strip defensive influence from a pitcher’s performance is FIP, which only considers strikeouts, walks, home runs, and hit-by-pitches. Because those events are independent of defensive skill, FIP provides a baseline for how a pitcher would perform with league-average defense. A consistent gap between ERA and FIP signals that defense (or luck on balls in play) is moving the pitcher’s results up or down. DeGrom’s career ERA (2.52) is slightly lower than his career FIP (2.65), indicating that, on the whole, the defense behind him has been a marginal net positive. However, the year-to-year variation reveals the unevenness of that support. In seasons with poor defense (e.g., 2018, 2020), the gap was actually larger — meaning deGrom was getting more help from defense despite the team’s low overall ranking. This paradox underscores that defensive quality is not uniform; a pitcher’s BABIP allowed and the types of contact he gives up determine how much help he receives.

Defensive Runs Saved (DRS) and Outs Above Average (OAA)

DRS measures how many runs a fielder saves over a league-average defender. Team-level DRS aggregates individual contributions. In deGrom’s 2019 season, the Mets’ DRS was +4 (14th), yet his ERA-FIP gap was -0.24. In 2021, the Mets’ DRS was -30 (27th), but deGrom’s ERA-FIP gap was -0.49 despite the awful team defense. This suggests that deGrom’s contact profile was so exploitable that the fielders — even if poor overall — could still handle the specific balls he allowed. Outs Above Average (OAA), which tracks expected catch probability, shows a similar story: the Mets ranked 22nd in OAA in 2021, but deGrom’s xBA (expected batting average) was just .207, meaning batters rarely made solid contact. The combination of extreme weak contact and high strikeout rates effectively insulates deGrom from defensive deficiencies, though not completely — his 2022 season with a .320 BABIP shows that even the best pitchers can be victimized by a porous defense.

Ground-Ball Tendencies and Defensive Alignment

DeGrom’s ground-ball rate has fluctuated between 42% and 48% over his career, peaking in 2018. Ground balls are generally more dependent on infield range and positioning than fly balls, which are more likely to be caught by outfielders. When a pitcher like deGrom induces a high number of grounders, the infield’s ability to move and react becomes paramount. In 2018, the Mets infield DRS was average (0), which supported deGrom’s ground-ball strategy. In 2020, the infield DRS fell to -7, and deGrom’s BABIP on ground balls rose to .280 (above league average). The 2021 infield was even worse (-11 DRS), yet deGrom’s BABIP on grounders dropped to .241 because his ground balls were so weakly hit that even subpar infielders could handle them.

Defensive Strategy Shifts and Their Effect on deGrom

The Role of Positioning and Shifts

In the modern game, teams use defensive shifts to align fielders where batters are most likely to hit the ball. For deGrom, opponents’ spray charts show a pronounced tendency to pull ground balls toward the left side of the infield (against right-handed batters). The Mets employed heavy shifts for deGrom, often moving the third baseman into the shortstop position and the shortstop into the second-base hole. According to Statcast data, the shift’s effectiveness for deGrom varied: in 2021, he had a shift success rate (outs generated from batted balls in shifted zones) of 62%, compared to a league average of 58%. When the shift succeeded, it turned would-be singles into routine outs, lowering his BABIP. When it failed — as it did in 2022 due to the Mets’ lack of range — it created larger holes for ground balls to sneak through.

Outfield Depth and Range

Outfield defense is often overlooked for a pitcher who strikes out many hitters, but fly balls do happen. DeGrom’s fly-ball rate averages around 35%, and he has allowed a career home run per nine innings of just 0.8 (excellent). Still, outfielders who cover more ground can turn warning-track fly balls into outs, preserving pitch counts and preventing extra-base hits. The Mets’ outfield DRS during deGrom’s peak was below average — in 2019, they ranked 23rd. Yet deGrom’s fly-ball BABIP was only .091 that year, meaning most of the fly balls he allowed that did not go for home runs were caught. This indicates either good positioning or weak contact. The Rangers in 2023 featured an outfield with higher OAA (Gold Glove caliber), and deGrom’s fly-ball BABIP fell to .063 — the lowest of his career — suggesting that superior range further amplified his results.

Comparative Analysis: deGrom vs. Other Elite Pitchers and Their Defensive Support

To contextualize deGrom’s experience, consider Clayton Kershaw during his peak with the Los Angeles Dodgers. From 2014 to 2017, the Dodgers’ defense ranked in the top five in DRS each year. Kershaw’s ERA-FIP gap averaged -0.24 runs per season, meaning his defense turned his already excellent FIP into an even lower ERA. Compare that to deGrom’s gap of -0.13 over his Mets career; while still positive, the magnitude is smaller. This suggests that deGrom had less defensive assistance than Kershaw, yet still achieved similar or better ERAs — a testament to deGrom’s ability to suppress quality of contact.

Max Scherzer offers another contrast. Scherzer’s career FIP (3.11) is higher than deGrom’s, but his ERA (3.16) is nearly equal. Scherzer has typically pitched for teams with good defenses (Nationals, Dodgers, Rangers), so the relatively small gap is not surprising. In 2019, Scherzer’s ERA was 2.92 and FIP was 3.00, with the Nationals’ defense ranking 6th in DRS. DeGrom’s 2019 numbers were better (ERA 2.43, FIP 2.67) despite a worse defense (14th in DRS). The difference in defensive context highlights deGrom’s superiority in generating weak contact and strikeouts — he doesn’t need elite fielders to thrive.

On the flip side, a pitcher like Kyle Hendricks, who relies heavily on contact management, is much more vulnerable to defensive quality. Hendricks’ ERA has swung wildly based on the Cubs’ defensive performance. In 2016, with a top-tier defense, his ERA was 2.13 (FIP 3.20, gap -1.07). In 2021, with a poor defense, his ERA ballooned to 4.77 (FIP 4.61, gap +0.16). deGrom’s narrow gaps (never exceeding 0.5 runs in either direction) underscore his relative independence from defensive support, but the gap still exists and can shift his ERA from historic to merely great.

Beyond ERA: How Defense Affects Game Management and Pitcher Strategy

Pitch Selection and Aggression

When a pitcher trusts his defense, he can challenge hitters in the strike zone more often, knowing that a well-struck ball may still be caught. Conversely, a pitcher who lacks trust may nibble at the edges, leading to deeper counts, more walks, and greater pitch counts. For deGrom, his fastball velocity (average 98 mph in his prime) and high chase rate allowed him to work aggressively regardless of the defense. However, subtle changes appeared: in 2018, with a poorer infield, deGrom increased his swing-and-miss offerings, throwing more sliders and changeups to generate whiffs rather than inducing ground balls that required fielding. His slider usage jumped from 23% in 2017 to 31% in 2018, reducing his ground-ball rate slightly but boosting his strikeout rate. This adjustment minimized defensive exposure.

Catcher Framing and Game Calling

While not part of team defense in the traditional sense, catcher framing affects how many pitches become strikes, which influences pitch count and the ability to put batters away. deGrom worked primarily with catchers Wilson Ramos (2017–2019) and James McCann (2020–2021), both of whom were below average in framing (around -5 to -7 runs per season). In 2022, the Mets used Tomas Nido and Patrick Mazeika, who were also poor framers. With the Rangers in 2023, deGrom threw to Jonah Heim, an elite framer (+6 runs). The improved framing likely helped deGrom get more called strikes, increasing his strikeout rate and reducing the number of balls in play. His strikeout rate rose to 33.4% with the Rangers, the highest of his career, partially attributable to framing. While framing is officially a catcher skill, its effect on a pitcher’s ERA is analogous to defensive support — it prevents balls in play without the pitcher having to throw strikes in the zone.

Historical Perspective: How deGrom’s Defensive Context Ranks Among Elite Pitchers

To understand whether deGrom’s ERA was artificially depressed or inflated by defense, it helps to compare his defensive support to other legendary arms. Greg Maddux famously pitched for the Atlanta Braves during a stretch when they led the league in defense multiple times (1992–1995). Maddux’s ERA-FIP gap from 1992–1995 averaged -0.49 runs, meaning his defense saved him nearly half a run per nine innings. deGrom’s best defensive years (e.g., 2019) produced a gap of just -0.24, lower than Maddux’s average. Yet deGrom’s raw ERA was often lower than Maddux’s best years. This reinforces the idea that deGrom’s dominance is so extreme that even modest defensive help puts him in rare air.

By contrast, Randy Johnson pitched for expansion teams and poor defensive clubs early in his career (Mariners, Astros). His ERA-FIP gap from 1990–1993 was +0.15 (ERA higher than FIP), meaning defense hurt him. Once he moved to the Diamondbacks with better defense, his gap flipped to -0.10. Johnson still won four Cy Youngs with a sub-3.00 ERA, but his defensive context clearly affected his numbers. deGrom’s consistent negative gap (ERA lower than FIP) suggests that, overall, the teams he played for have been slightly better at converting his batted balls into outs, even if their overall defensive rankings were poor — a testament to the weakness of the contact he allows.

Conclusion: Defense as a Force Multiplier, Not a Prerequisite

Jacob deGrom’s career demonstrates that elite pitchers can overcome below-average defense to post historic ERAs, but the relationship is not a one-way street. The quality of defense behind him has added or subtracted 0.2 to 0.5 runs from his ERA in any given season, enough to separate an All-Star season from a Cy Young season or a Cy Young season from a generational outlier. The 2018 season — arguably his best — was helped by a defense that, while poor overall, managed to handle the weak contact deGrom induced. The 2022 season showed what happens when a mediocre defense meets a pitcher coming off injury and unable to miss bats at the same rate: a gap that cost him valuable fraction of a run per nine.

For pitchers and coaches, the lesson is clear: while strikeouts and weak contact are the most reliable paths to a low ERA, investing in defensive quality — whether through positioning, range, or catcher framing — amplifies a pitcher’s results. For deGrom, the move to the Rangers in 2023 provided a glimpse of what happens when an elite pitcher pairs with an elite defense: an ERA so low it redefines expectations. As analytics continue to parse the contributions of fielders, deGrom’s career will remain a case study in how the interplay between pitching and defense shapes the numbers we use to measure greatness.

Ultimately, Jacob deGrom’s overall ERA is not purely a reflection of his own ability — it is a product of his dominance, the defenders who react to each batted ball, and the strategic decisions of the team behind him. Recognizing this relationship allows fans, students, and coaches to evaluate pitchers with a more nuanced lens, one that appreciates the collective effort required to turn a baseball into an out. For deGrom, the defense has been a quiet partner in his masterpiece — occasionally imperfect, but when aligned, capable of transforming a great pitcher into a legend.