The Giants Have Been Way Off BaseRuns

This season was supposed to be something different for the Giants. Following last year’s 81-81 finish, president of baseball operations and franchise icon Buster Posey went outside the box to hire manager Tony Vitello straight from the college ranks, and added free agents Luis Arraez and Harrison Bader to upgrade a couple of the lineup’s dead spots. Throw in a full season of mid-2025 acquisition Rafael Devers, and the team had reasonable hope of reaching the playoffs for the first time since 2021, and just the second time in the past 10 seasons. Instead, the 2026 Giants haven’t spent a day over .500, and at 58-83, they own the National League’s second-worst record. Like the Tigers, they’re in danger of making some dubious history, in their case by falling short of their BaseRuns-projected win total by the largest margin of any team since 2002.
As I explained on Thursday, the Tigers are nearly 11 full wins short of their Pythagorean-projected win total, an estimate based upon their totals of runs scored and runs allowed using the formula Winning % = RS^2 /(RS^2 +RA^2). Out of all the teams playing full seasons in the Wild Card era (not the strike-shortened 1995 season or the pandemic-shortened 2020 season, but including 2026 for the purposes of comparison), that’s the third-largest shortfall.
Where Pythagorean projections use actual runs scored and allowed to calculate an expected winning percentage, BaseRuns uses estimated runs scored and allowed, derived from familiar statistical components such as hits, walks, hit-by-pitches, stolen bases, and so on. Those run estimates are then plugged into the Pythagenpat formula — a variant of Bill James’ Pythagorean formula where the exponent itself is a function of the scoring environment via the formula X = ((RS + RA)/G)^0.287 — for a second-order estimate of winning percentage. Both the Pythagorean and BaseRuns estimated winning percentages provide useful if imperfect ways of measuring teams’ underlying performance and helping to identify outliers in either direction. Read the rest of this entry »






