2027 ABS challenge policy
The question
What challenge rules does the staff run in 2027?
Recommendation
Confidence LowKeep challenging as the staff does now, with the break-even card as the written rule so the old grid isn't used: catchers own the defensive challenges; challenge a call when you're at least as sure as its count's break-even: 6%–32% with both challenges left before the 7th, 13%–53% with the last one before the 7th, 3%–17% from the 7th inning on. Early in the game, batters with the last challenge hold 0-0 and 0-1 through the 2nd and 1-1 through the 1st, unless the call is clear. No green lists. Against how clubs already challenge, the card is a toss-up (≈0 runs a season, 80% range −0.04 to +0.05, inside the plan's 1.9-run toss-up line). It would have held back none of Pittsburgh's 196 second-half challenges. Don't go back to the old count grid: in the forward test it cost about 9.4 runs per club a season, late-game exception included.
Decided together with “Tender or non-tender, and the third catcher”; both read the same Winter Plan.
No clear lean on the card itself: against how clubs already challenge, its forward-tested 80% range (−0.04 to +0.05 runs a season) sits inside the plan's 1.9-run toss-up line, so adopting it is a judgment call. The clear part is the old grid: it lost 9.4 runs per club a season in the forward test, 8.9 even at the good end of its range. The test scores 5,227 second-half challenges on rules fit before Jul 1.
Evidence
- Pittsburgh won 47.0% of its 355 challenges (30th of 30; MLB 53.9%), −6.4 runs against an average club facing the same pitches. Accuracy in the spots it chose accounts for 5.9 of those runs, the accuracy gap. Regressed, 2026's club accuracy is worth about 8 overturns at 2026 volume; its catcher part moves if the catchers change.
- A failed challenge costs about 0.03 runs under the rules as played (Savant's run values by game state), not the flat 0.21 the old count grid assumed. So the bar for a challenge depends on the game state as well as the count. The card's break-evens, from count to count: 6%–32% with both challenges left before the 7th, 13%–53% with the last one before the 7th, 3%–17% from the 7th inning on.
- The forward test (rules fit on the 5,330 challenges before Jul 1, scored on the 5,227 after it, per club over a season): the card is worth ≈0 runs (−0.04 to +0.05, 80% range) against how clubs already challenged, inside the plan's toss-up line (1.9 runs, 0.2 wins). The old count grid (early counts held; no hold from the 7th inning on with no challenge lost yet and the score within 2 runs) cost 9.4 runs (8.9–9.9), about 1.0 wins. Pittsburgh's own second half: the card would have held back none of its 196 challenges, the old grid 110.
- Catchers already make most defensive challenges: 175 of 192 in 2026, at 52% (league catchers 59%).
- Is accuracy a skill? Odd vs. even challenges: batters r = −0.05 (−0.20 to 0.09, 182 hitters); catchers r = 0.08 (−0.02 to 0.19, 338 player-seasons). Neither is shown to repeat, so there are no green lists.
- Not measured: challenging more might add runs (573 overturnable calls went unchallenged), but the data can't say how sure players were on calls they let go.
- The plan's catchers: Endy Rodríguez, Rafael Flores Jr. and Christian Bethancourt.
Options considered
| Option | Upside | Downside |
|---|---|---|
| Keep challenging as now, with the break-even card written downRecommended | ≈0 runs a season against how clubs challenged (80% range −0.04 to +0.05), a toss-up; it keeps the old grid's 9.4-run cost off the table | Adds no runs by itself: the gain would come from accuracy or from challenging more, which isn't measured |
| The old count grid (early counts held; no hold from the 7th inning on with no challenge lost yet and the score within 2 runs) | A simple rule | −9.4 runs per club a season in the forward test (≈−1.0 wins) |
| Status quo, nothing written down | No change management | Nothing keeps the old grid out of use; 2026 finished 30th of 30 at winning challenges, mostly accuracy that regresses on its own |
Risks
- Players may resist a bar set by game state rather than feel.
- The zone or the challenge rules could change for 2027.
- The cost of a failure is Savant's run value by game state; a club's own game-state model could move the bars.
What would change our mind
If spring pilots show a challenger's success repeating (a real skill), give him a looser bar; if the challenge rules change, refit the card.