CB Bucknor
2 games graded behind the plate.
338 correct of 369 graded takes (91.6% ± 2.8, 95%). Best game 95.2% · worst 89.2%. 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 CB Bucknor
This season is 369 graded takes, which puts CB Bucknor's overall accuracy at 91.6% ± 2.8 (95% interval). That interval is a large share of the whole league's four-point spread, so this grade is a reading and not yet a ranking — we print it, and we do not place it against umpires with a full season behind the plate. Everything finer is further out of reach still:
- how the zone moves with two strikes — about 74 takes, so ±6.3 points. (the league-wide two-strike effect is about 1 point in 2026.)
- any single corner of the zone — about 31 takes, so ±9.8 points. (corner cells are where umpires actually differ.)
- whether one pitcher is called tighter than another — about 6 takes, so ±22.2 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 9 pitches players chose to challenge, which are the pitches they already believed were wrong. At 9 challenges it is far too thin to rank at all — the interval is roughly ±27.2 points — so we print it beside its denominator and keep it off every leaderboard.