Bottom line: San Francisco's -65 luck index is MLB's largest negative divergence, and the data says their record is lying about who they are.
Through September 27, 2026, the final week of the MLB regular season is exposing some of the widest gaps between expected and actual performance we've tracked all year. Per Baseball Savant's Statcast-derived run expectancy models, several teams have records that bear little resemblance to the quality of baseball they've been playing. The mlb luck index, which synthesizes run differential, expected win-loss based on base-out run expectancy, and bullpen sequencing variance into a single score, tells a story the standings refuse to.
Here are the six clubs sitting at the extremes.
Due a Correction
| Team | Luck Index | xPoints Gap |
|---|---|---|
| Giants | -65 | -6.50 |
| Tigers | -59 | -12.30 |
| Angels | -50 | -8.70 |
San Francisco Giants. A luck score of -65 is the most extreme in baseball right now. The Giants' xPoints gap of -6.50 means they should have roughly six to seven more wins than their actual record reflects. Their pitching staff has posted a 3.68 xFIP while allowing runs at a 4.21 clip, a disconnect driven largely by a .319 BABIP against that sits well above league average. Sequencing has been merciless. Teams carrying this kind of negative variance in September have historically closed roughly 60% of the gap over the following 15 to 20 games, per historical Statcast modeling.
Detroit Tigers. The most staggering number on this list belongs to Detroit: an xPoints gap of -12.30, meaning their Pythagorean expectation suggests they should have 12 more wins. A -59 luck index confirms the gap isn't a model quirk. The Tigers' record in one-run games is 22-41, a split that almost never sustains. They've been competitive far more often than their place in the standings suggests.
Twelve wins is a lot of baseball to leave on the table.
Los Angeles Angels. At -50 on the luck index with an 8.7-win deficit to expected performance, the Angels have been ground down by a bullpen that has converted a 3.44 xFIP into a 4.19 ERA. Their relievers rank 11th in strikeout rate but 27th in actual ERA, the kind of gap that screams strand-rate misfortune. The market has been pricing the Angels as a below-average team. The underlying numbers suggest something closer to mediocre, which in betting terms is a meaningful distinction.
Living on Borrowed Luck
| Team | Luck Index | xPoints Gap |
|---|---|---|
| Rays | 82 | +7.90 |
| D-backs | 50 | +4.10 |
| Reds | 46 | +9.80 |
Tampa Bay Rays. An 82 luck index is the highest positive score in MLB this season. The Rays are nearly eight wins above their expected record, propped up by a .224 opponent BABIP with runners in scoring position that sits miles below any sustainable baseline. Tampa's ability to win ugly is legendary, but even by their standards, the sequencing has been cartoonishly kind.
Arizona Diamondbacks. A +50 luckscore and a 4.1-win surplus over expected performance. Arizona's offense has a .278 BABIP that aligns with talent, but their pitching staff has benefited from a strand rate north of 76%, well above the league mean of 72%. That gap tends to narrow.
Cincinnati Reds. The Reds carry a 9.8-win surplus over their expected record, the largest positive xPoints gap in the majors. Their 34-19 mark in one-run games is, statistically, unsustainable. Bookmakers tend to adjust slowly to these signals, which means the line can lag the data by weeks.
The Regression Window
In MLB, variance of this magnitude typically corrects over a 20-to-30 game window, though the final week of the regular season compresses the timeline. Historically, teams with a luck index beyond plus or minus 50 see roughly half the gap close within the next month of play. For clubs headed to October, that correction doesn't pause for the postseason. It accelerates. Small samples, high leverage, and bullpen-heavy usage tend to strip the noise away fast.
The data doesn't care about narratives. It just waits.