Giants at 58-83 Are on Pace for One of the Worst BaseRuns Gaps Since 2002

At 58-83, the 2026 San Francisco Giants have not spent a single day above .500, and according to Jay Jaffe, their season may be heading toward a historically unusual destination: the fourth-largest gap between actual wins and BaseRuns-projected wins of any team since 2002.

What BaseRuns is measuring

BaseRuns differs from the more familiar Pythagorean win estimator in one important way. Where Pythagorean projections work backward from actual runs scored and allowed, BaseRuns constructs estimated run totals from underlying components — hits, walks, hit-by-pitches, stolen bases, and similar inputs — and then feeds those estimates into the Pythagenpat formula, a variant of Bill James' Pythagorean formula in which the exponent is itself a function of the scoring environment. The result is a second-order expected winning percentage: a measure of how a team should be performing given the quality of contact and plate discipline it has generated, independent of whether those events happened to cluster in high-leverage moments.

When a team's actual record falls well short of that estimate, it typically signals some combination of bad timing, poor performance in close situations, or outcomes that the underlying components suggest were unlikely to persist.

The Giants' company in the dubious ledger

Per Jaffe's piece, the Giants share the bottom of this particular list with a couple of other teams from this same 2026 season. The Giants' situation is measured on the BaseRuns side of the ledger, but the underlying story is familiar: a team whose component performance suggests it should be meaningfully better than its record.

The season's backdrop

The 2026 Giants were constructed with genuine optimism. Buster Posey, the franchise's president of baseball operations, hired Tony Vitello away from the college ranks to manage the club, added Luis Arraez and Harrison Bader in free agency to address lineup weaknesses, and had a full season of Rafael Devers — a mid-2025 addition — to look forward to. The record has not cooperated, and the club owns the National League's second-worst mark.

Posey reportedly confirmed, per a previously reported Posterior item, that Vitello will return as manager in 2027 despite the difficult debut season. The roster has been in active September flux as well, with the Giants expanding to 28 players and calling up prospects including LHP Cesar Perdomo and Yunior Marte, who came directly from Double-A for his MLB debut.

What remains unresolved

Jaffe's analysis identifies the Giants as a significant outlier but does not attribute the gap to any single cause — the piece frames it as a measurement of underperformance relative to underlying components, not a diagnosis. Whether the gap closes meaningfully over the final stretch of the season, or whether San Francisco finishes with one of the largest BaseRuns shortfalls on record, remains an open question.