Umpire Grade · Blue Notes

Laz Diaz

26 games graded behind the plate.

Season Grade

91.6% ± 0.9

Avg Swing

runs / game

ABS Overturns

70/117 calls

3,586 correct of 3,914 graded takes (91.6% ± 0.9, 95%). Best game 94.2% · worst 88.0%. 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 Laz Diaz

This season is 3,914 graded takes, which puts Laz Diaz's overall accuracy at 91.6% ± 0.9 (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 783 takes, so ±1.9 points. (the league-wide two-strike effect is about 1 point in 2026.)
any single corner of the zone — about 326 takes, so ±3.0 points. (corner cells are where umpires actually differ.)
whether one pitcher is called tighter than another — about 65 takes, so ±6.7 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 117 pitches players chose to challenge, which are the pitches they already believed were wrong. 117 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

Laz Díaz

A former minor leaguer who found umpiring through weekend softball beer leagues and has spent 31 years in the majors.

The road to the major leagues started with slow-pitch softball. A friend going through a divorce suggested they umpire beer leagues together on weekends, and Laz Díaz said yes. From beer leagues they progressed to high school games and then to college ball. When his own life shifted, another friend encouraged him to attend the Harry Wendelstedt Umpire School in Daytona. Díaz was one of the top students coming out of umpire school, which helped him secure a job and work his way up through the minors to the major leagues.

Before the beer leagues, he had tried to make it as a player. Born March 29, 1963, in Miami, Florida, Díaz played high school and college baseball before joining the Twins organization in 1984. The Twins released him, and he tried out with the Cardinals in 1985 but got hurt. He attended Yankees spring training in 1987 before being let go. At that point he decided he was done playing.

He umpired his first major league game on June 23, 1995. Across 31 years in the majors, he has recorded 50 ejections and drawn assignments in multiple World Series and All-Star Games. He was promoted to crew chief in 2022, becoming only the second full-time Latino to hold that role. A former minor league player and Marine Corps Reservist, Díaz works behind the plate in 2026. We have graded him behind the plate in 20 games this season, and the record on this page is the reason his name is here.

Reporting: Society for American Baseball Research, Baseball Almanac. Umpire data: MLB StatsAPI, via the Fever engine.

By the Desk · filed 2026-07-23 — 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
MIA @ WSH2026-08-28	B-	0.1 MIA	3/5	Pitchers earned every strike the hard way.
STL @ PHI2026-08-23	B+	0.2 PHI	2/4	An honest evening's grade: nothing loud, nothing missed by much.
SD @ NYM2026-08-18	A-	1.2 SD	4/5	Two dugouts, and only one of them smiling.
CIN @ WSH2026-08-07	B-	0.2 CIN	0/2	Expanded the plate a touch past its 17 inches.
LAD @ CHC2026-08-04	B+	0.1 CHC	2/2	Down the middle. Both dugouts had the same zone.
KC @ DET2026-07-24	D	0.5 DET	2/3	Pitchers found a little extra real estate.
LAD @ PHI2026-07-20	B+	0.5 LAD	4/5	The kind of night where the umpire is the least of the story.
LAA @ MIN2026-07-12	B	0.0 LAA	1/4	The black wasn't in play tonight.
SEA @ MIA2026-07-08	B	0.2 SEA	3/3	The zone stretched its legs.
BAL @ CIN2026-07-03	D	0.7 CIN	6/7	Hawkeye did more talking than the umpire tonight.
CIN @ NYY2026-06-20	D	1.6 NYY	2/4	The corners were friendlier in one direction tonight.
SD @ STL2026-06-15	B+	0.8 STL	0/0	A workmanlike night — nothing to frame, nothing to fix.
SEA @ DET2026-06-07	C	0.7 SEA	5/9	This one went to video review more than most.
CLE @ NYY2026-06-03	D	1.0 CLE	5/6	ABS had a long evening on this one.
COL @ LAD2026-05-27	B+	0.3 LAD	1/4	A steady night's work behind the plate.
ATH @ SD2026-05-23	B	0.2 SD	2/4	The black wasn't in play tonight.
BOS @ KC2026-05-18	B-	0.0 BOS	2/4	One of those nights the numbers won't flatter.
CHC @ CWS2026-05-15	B	0.2 CHC	2/5	The zone kept its promises.
HOU @ BOS2026-05-03	D	0.3 HOU	6/9	This one went to video review more than most.
STL @ PIT2026-04-29	B	0.2 STL	3/5	Down the middle. Both dugouts had the same zone.
DET @ CIN2026-04-25	B	0.7 DET	3/6	An honest evening's grade: nothing loud, nothing missed by much.
ATL @ WSH2026-04-21	B	0.3 ATL	2/5	Reliable as a Tuesday: no complaints, no headlines.
SF @ BAL2026-04-10	C+	0.3 BAL	1/1	A small strike zone, generously enforced for the offense.
SD @ BOS2026-04-05	B+	0.4 BOS	3/3	An honest evening's grade: nothing loud, nothing missed by much.
COL @ TOR2026-03-31	B-	1.2 TOR	3/7	One side pitched to a slightly bigger plate.
MIN @ BAL2026-03-26	C+	0.8 BAL	3/5	The zone had wings tonight.