Minor-League Translations

The same hitters’ next-season MLB wOBA (2025 AAA → 2026 MLB) and WAR per 600 PA for call-ups.

• Every 2025–26 line at AAA, AA, High-A and Single-A, and in the majors (MLB Stats API)
• AAA Statcast batted balls (expected wOBA)
• FanGraphs 2026 prospect board (Future Value grades)
• The Winter Plan’s roster, depth chart and decisions feed

• Factor per rate = Σ w·rate(upper) / Σ w·rate(lower) over players with 100+ PA at both levels the same season, w = harmonic mean PA; chained down from the majors
• Season-matched: each pair’s rates are read against his season’s league at each level before the two seasons are pooled, and a season’s lines get that season’s environment back. The 2026 lower minors scored far more than 2025’s (Double-A wOBA .303 → .330) while Triple-A barely moved; pooled raw, the Triple-A−Double-A gap ran .008 to .024 depending on the season’s pairs, and season-matched it is .024–.027 either way
• Scored on every 2025 AAA hitter (150+ PA) who reached the majors in 2026, at any number of plate appearances, each weighted by his MLB PA: keeping only those who reached 100 PA selected on the outcome and made a AAA-average call-up look about .008 wOBA better than he is (that fit is kept as a check)
• Readiness for tracked AAA hitters: MLB wOBA on AAA expected wOBA (PA-weighted, leave-one-out scored), read against the scoring season’s AAA average; samples under 150 tracked PA shrunk further by the split-half reliability of AAA expected wOBA, with a wider range for the talent variance they no longer explain
• Everyone else: the translated line regressed toward his level’s average translated line, then shrunk within his level by a held-out fit (the season-matched gap between level averages is kept, so an average High-A line doesn’t rate like a Triple-A call-up)
• An 80% range on each estimate from the model’s error on true talent (held-out error less the outcome noise of the hitters’ MLB plate appearances). Translated lines were fit at AAA and scored again on 2025 Double-A hitters who reached the majors: Double-A ranges take that test’s much larger error; High-A (too few call-ups to test) borrows it, labelled untested. A short MLB record is shown beside the estimate, since blending it in didn’t help on the test
• Double-A step checked a second way, less selected: 2025 Double-A hitters who played in Triple-A in 2026, their line stepped up with 2025’s factors, against Triple-A hitters who repeated the level. Both checks say Double-A lines read low, so the level gap is the least certain piece; point estimates are not shifted for it
• Internal options (Pittsburgh): ranked by expected MLB wOBA, with each neighbour marked a toss-up when the gap is inside the 80% range of the difference (both ranges, plus the level-gap uncertainty when the two come from different levels or methods)
• MLB veterans: 250+ career MLB PA (batters faced, for pitchers), seasons before 2024 counted from FanGraphs’ season tables since our MLB lines start in 2024; badged, listed as depth, and left out of the headline bat
• The plan’s thin-record players: each shown with what the plan’s engine rates him on (his MLB record from about 150 weighted PA last season, Triple-A contact quality blended with his grade, or his grade’s cap); the minor-league read is greyed where the engine doesn’t use it
• Depth chart, thin-record hitters with 100+ tracked AAA PA: 60% the AAA estimate + 40% the prospect-grade rate, plus his position. The call-up test scores exactly that formula; the held-out fits chose 55–65%
• Call-up test held out throughout: each player’s AAA estimate comes from a model fit without him, his position from his 2025 AAA line, the blend weight chosen without him; a seeded bootstrap gives the weight’s range and the blend’s edge over an average call-up
• Pitchers: translated K, BB+HBP and HR rates regressed toward the average pitcher at his own level, as FIP. Scored blind on 2025 AAA arms against their 2026 MLB FIP, it ran high and missed by more than guessing the average, so it ranks; Double-A and High-A are untested

• One season of AAA → MLB outcomes (218 hitters, many with few PA): the best blend weight could sit anywhere from about 35% to 80%.
• Scored honestly, no rating beats “an average call-up”: contact quality ranks call-ups only about as well as prospect grades do.
• Same-season pairs are players who moved mid-year, and clubs promote hot hitters, so factors run harsh.
• No defense or baserunning in the minor-league estimates; position adjustment assumes an average glove.
• Pitcher readiness isn’t predictable from these data (r .07–.19 on the three tests: AAA K−BB%, AAA Stuff, translated FIP); pitchers are ranked, not forecast.
• Double-A lines read low on both checks (the majors, and next season’s Triple-A), and one season of each can’t say how much is a harsh factor and how much is young hitters developing; calls across levels inside that are toss-ups.

• 2027 MLB results of the hitters rated here
• Whether the blend beats the grade rule and an average call-up on the 2027 class