Nick Mahrley
28 games graded behind the plate.
Nick Mahrley called 91.8% of taken pitches correctly in the 2026 regular season — 76th of 81 plate umpires with a full season’s sample. League rate: 92.8%.
3,997 correct of 4,354 graded takes (91.8% ± 0.8, 95%). Best game 96.3% · worst 86.9%. Grade is accuracy on taken pitches vs the rulebook zone; ABS is the Automated Ball-Strike System challenge record (how often the robots overruled the call).
What we can't say about Nick Mahrley
This season is 4,354 graded takes, which puts Nick Mahrley's overall accuracy at 91.8% ± 0.8 (95% interval). That is a real measurement against a league spanning about four points end to end. It is not enough for anything finer, and here is the arithmetic rather than our word for it:
- how the zone moves with two strikes — about 871 takes, so ±1.8 points. (the league-wide two-strike effect is about 1 point in 2026.)
- any single corner of the zone — about 363 takes, so ±2.8 points. (corner cells are where umpires actually differ.)
- whether one pitcher is called tighter than another — about 73 takes, so ±6.3 points. (a given pitcher is worked once or twice a season.)
And a note on the number itself: an accuracy figure is a rate plus a convention for what counts as a miss. Ours grades every taken pitch against the rulebook zone as the feed reports it. Others are more forgiving — UmpScorecards counts a call wrong only when the pitch was at least 90% likely to be a strike — so two sites can print the same percentage about the same umpire and not mean the same thing by it. How the grade is built.
The overturn rate is a different kind of number and does not belong beside the grade: it is accuracy on the 108 pitches players chose to challenge, which are the pitches they already believed were wrong. 108 is enough to print it with its own denominator, which is what we do — but it still ranks umpires by how often they are appealed, not by how often they are right.
The road to the plate
The Back Fields
Nick Mahrley served in the Air Force before a Spring Training visit sent him to umpire school. He reached the majors in 2017 and the permanent staff in 2023.
After his service in the United States Air Force ended, Nick Mahrley found himself at Spring Training in Arizona. He had spent his military years working on survival systems and ejection seat components for F-16 aircraft. Watching umpires work the back fields there, he noticed they were about his age. He had umpired some as a high schooler, and that realization reignited the interest. He decided to attend umpire school.
The minors began in 2007 and carried him through the Gulf Coast League, the Midwest League, the Eastern League, and the Pacific Coast League. He debuted on August 3, 2017, at Coors Field, working a Mets-Rockies game alongside Lance Barrett, Brian Knight, and Jim Reynolds. After years of splitting time between the minors and the majors as a call-up, he finally became a full-time MLB umpire on 2023 Opening Day. A record-high ten umpires had retired following the 2022 season, and Mahrley filled one of the open seats.
He wears number 48 and works on Crew J, whose crew chief is Marvin Hudson. On August 25, 2024, Mahrley was behind the plate at Yankee Stadium when the barrel of Giancarlo Stanton's broken bat struck him on the side of his neck. He was carted off the field and later diagnosed with a concussion. That fall, his first postseason assignment followed: the 2024 American League Division Series between the Cleveland Guardians and the Detroit Tigers.
This season, 17 of his games behind the plate appear in our grading record.
Reporting: MLB.com, Wikipedia. Umpire data: MLB StatsAPI, via the Fever engine.
By the Desk · filed 2026-07-24 — the profile reads as of its filing; the grading record above is live · every fact in this piece comes from a sourced research pack and clears an independent fact-check, and nothing is edited after filing.
October behind the plate
Playoff games are graded on their own and are not part of the season grade above.
The games
| Game | Grade | Favor | ABS | Blue Note |
|---|---|---|---|---|
| LAD @ SF2026-09-26 | C+ | 1.5 LAD | 2/5 | Somebody's pitching staff sent a thank-you note. |
| MIA @ SD2026-09-20 | C+ | 0.3 SD | 2/3 | Borderline went to the battery all night. |
| BOS @ TEX2026-09-16 | C | 0.5 TEX | 8/8 | The challenge cart got its steps in. |
| NYM @ NYY2026-09-11 | B | 0.5 NYM | 4/5 | Borderline went to the battery all night. |
| MIN @ CWS2026-09-05 | B+ | 0.5 CWS | 2/4 | Generous with the corners — the pitchers said thank you. |
| MIL @ CHC2026-09-01 | C+ | 0.2 CHC | 3/5 | You had to throw it down Broadway to get the call. |
| PIT @ STL2026-08-28 | B+ | 0.1 PIT | 1/1 | A steady night's work behind the plate. |
| COL @ WSH2026-08-24 | B+ | 0.1 WSH | 2/6 | The zone kept its promises. |
| TEX @ LAA2026-08-10 | B | 0.0 LAA | 2/3 | If it was close, it was a strike. The hitters noticed. |
| KC @ MIN2026-07-30 | D | 0.2 KC | 3/6 | Generous with the corners — the pitchers said thank you. |
| SEA @ TEX2026-07-26 | B- | 0.3 SEA | 1/3 | Generous with the corners — the pitchers said thank you. |
| DET @ CHC2026-07-21 | D | 1.0 DET | 1/1 | The zone had wings tonight. |
| MIA @ MIL2026-07-17 | D | 1.0 MIA | 3/5 | The zone stretched its legs. |
| KC @ BAL2026-07-10 | B+ | 0.2 KC | 0/1 | The kind of night where the umpire is the least of the story. |
| SD @ LAD2026-07-05 | D | 0.1 SD | 2/6 | Expanded the plate a touch past its 17 inches. |
| SF @ AZ2026-07-01 | A | 0.1 SF | 0/1 | An honest evening's grade: nothing loud, nothing missed by much. |
| ATH @ LAA2026-06-27 | B | 0.0 LAA | 3/3 | Squeezed the edges; the hitters didn't mind at all. |
| CLE @ CWS2026-06-22 | B | 1.1 CWS | 3/7 | A tilt to the evening — the numbers say which way. |
| ATH @ HOU2026-06-05 | C+ | 1.2 HOU | 2/4 | The grade leaned — the ledger says which way. |
| ATL @ CIN2026-05-31 | C+ | 0.7 ATL | 2/5 | The zone stretched its legs. |
| NYY @ KC2026-05-26 | B- | 0.4 NYY | 1/2 | Solid and unspectacular — exactly what the job asks. |
| LAD @ MIL2026-05-22 | A- | 0.5 MIL | 0/2 | Reliable as a Tuesday: no complaints, no headlines. |
| AZ @ COL2026-05-17 | B+ | 0.1 COL | 2/3 | Called a fair game and let the players decide it. |
| COL @ NYM2026-04-24 | B | 0.5 COL | 5/6 | Hawkeye did more talking than the umpire tonight. |
| CWS @ KC2026-04-12 | B | 0.8 KC | 1/2 | Called a fair game and let the players decide it. |
| SD @ PIT2026-04-08 | A | 0.6 PIT | 3/4 | Down the middle. Both dugouts had the same zone. |
| TB @ MIN2026-04-04 | B+ | 1.1 TB | 1/4 | Somebody's pitching staff sent a thank-you note. |
| WSH @ PHI2026-03-30 | A | 0.2 PHI | 1/3 | Generous with the corners — the pitchers said thank you. |
→ all 91 umpire grades, sortable
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