Umpire Grade · Blue Notes

Cory Blaser

23 games graded behind the plate.

Season Grade

93.1% ± 0.8

Avg Swing

runs / game

ABS Overturns

66/108 calls

3,338 correct of 3,584 graded takes (93.1% ± 0.8, 95%). Best game 98.6% · worst 89.9%. 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 Cory Blaser

This season is 3,584 graded takes, which puts Cory Blaser's overall accuracy at 93.1% ± 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 717 takes, so ±1.9 points. (the league-wide two-strike effect is about 1 point in 2026.)
any single corner of the zone — about 299 takes, so ±2.9 points. (corner cells are where umpires actually differ.)
whether one pitcher is called tighter than another — about 60 takes, so ±6.4 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 Job He Didn't Like

How a Denver teenager's first umpiring job began with his father and a job he didn't like.

Cory Blaser was 14 or 15, working a job at Target he did not like, when his father suggested he try umpiring. His father was a longtime Colorado high-school umpire. Blaser worked Little League and summer high-school games around Denver, where he was born in 1981 and graduated from Pomona High School. He promised his father he would finish two years at Colorado State University before going to umpire school, and he kept that promise — enrolling at the Harry Wendelstedt Umpire School in 2002.

He spent twelve full years in the minor leagues, moving through the Arizona League, the Northwest League, the Carolina League, the Eastern League, and the Pacific Coast League. He filled in at the major league level for four or five seasons before being hired to the full-time staff in January 2014. His first MLB game had come on April 24, 2010.

Postseason assignments followed. He worked his first playoff game in right field on October 7, 2015, at the National League Wild Card Game between the Cubs and the Pirates. Division Series calls came in 2016, 2017, 2018, 2022, 2023, and 2024; League Championship Series in 2019 and 2020; the All-Star Game in 2018. During the 2026 World Baseball Classic, a strike call of his with two strikes drew attention after it contributed to the Dominican Republic's loss — one game in a tournament setting, outside the major league schedule that makes up the bulk of his year.

We have graded him behind the plate in 17 games this season. He also works as an offseason instructor at the Harry Wendelstedt Umpire School.

Reporting: SABR, Wikipedia, MLB.com. 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.

The games

Game	Grade	Favor	ABS	Blue Note
BAL @ STL2026-08-25	B-	0.9 BAL	4/6	A steady night's work behind the plate.
ATH @ KC2026-08-20	A-	1.0 KC	3/5	Tonight's zone had a rooting interest.
PHI @ MIN2026-08-16	C+	0.7 MIN	1/4	Generous with the corners — the pitchers said thank you.
NYM @ ATL2026-08-10	C	0.8 NYM	5/7	The players kept asking for a second opinion — and kept getting one.
STL @ NYY2026-08-05	B+	1.1 NYY	4/8	Somebody's pitching staff sent a thank-you note.
CHC @ PIT2026-07-25	A-	0.3 PIT	5/5	Hawkeye did more talking than the umpire tonight.
NYM @ MIL2026-07-20	A	0.8 NYM	3/4	Reliable as a Tuesday: no complaints, no headlines.
TB @ HOU2026-07-05	C+	0.0 TB	5/6	The players kept asking for a second opinion — and kept getting one.
PIT @ PHI2026-07-01	B-	1.3 PHI	3/6	The corners were friendlier in one direction tonight.
WSH @ BAL2026-06-27	A-	1.5 WSH	5/7	The challenge cart got its steps in.
TEX @ MIA2026-06-22	A+	0.4 MIA	1/3	A workmanlike night — nothing to frame, nothing to fix.
SEA @ WSH2026-06-12	B	0.7 WSH	1/1	Solid and unspectacular — exactly what the job asks.
SF @ CHC2026-06-07	A-	0.2 CHC	4/6	A steady night's work behind the plate.
KC @ CIN2026-06-03	C+	0.8 CIN	0/2	You had to throw it down Broadway to get the call.
NYM @ MIA2026-05-22	A-	0.2 MIA	4/6	Called a fair game and let the players decide it.
SF @ ATH2026-05-16	C+	0.3 ATH	2/4	Nothing off the plate, and not much on the black either.
AZ @ TEX2026-05-12	A+	0.5 TEX	1/2	Down the middle. Both dugouts had the same zone.
STL @ SD2026-05-08	B	0.8 SD	3/3	Expanded the plate a touch past its 17 inches.
CWS @ LAA2026-05-04	A-	0.6 CWS	1/5	The kind of night where the umpire is the least of the story.
CWS @ AZ2026-04-23	B	0.8 AZ	3/7	Nothing that'll trend, and on this beat that's a compliment.
KC @ DET2026-04-14	B	0.4 KC	2/3	Borderline went to the battery all night.
MIN @ KC2026-04-02	B+	0.6 KC	3/4	The kind of night where the umpire is the least of the story.
AZ @ LAD2026-03-27	B+	0.2 AZ	3/4	Down the middle. Both dugouts had the same zone.