Less than a third of the season remains, and most major-league teams are winning about as many game as their runs scored and allowed suggest. Nineteen of the 30 teams are within three games of their Pythagorean projection and all but the Blue Jays (eight games below projection) and Athletics (nine below) are within five.
Through Sunday’s games, the Cubs and White Sox are tied with the Mariners for the top spot in outperforming Pythagorean. All are at plus-5 games, using the formula winning percentage = runs squared/(runs squared plus runs allowed squared). The Cubs have scored 463 runs and allowed 431, a combination that typically would lead to a 62-54 record instead of their current 67-49. The Sox’ 433 runs scored and 498 allowed suggests 50-65, rather than their actual 55-60.
Differences between Pythagorean and actual records can be influenced by random factors such as unusual runs of clutch hitting, for better or worse, extreme bullpen success or failure, and unusual records in close games.
The Cubs and Sox both have performed better than their overall records in one-run games. The Cubs are 27-17, a .614 winning percentage, in one-run games, and 40-32, .556, in other games. The Sox are 22-22, .500 in games decided by one run, and 33-43, .434, in others.
There is no tendency for chance factors to continue. Most of the time you’d expect teams that are far above or below their projections to play closer to Pythagorean the rest of the way.
FanGraphs.com takes an extra step with its Base Runs standings. The idea is that there are not only chance factors affecting wins and losses, there are chance factors affecting runs and runs allowed. So it uses using David Smyth’s BaseRuns as a base to calculate how many runs a team normally would score and allow given its component stats, then projects standings from there.
The White Sox’ BaseRuns record of 50-65 is the same as its Pythagorean. The Cubs show at 63-53 in BaseRuns, one game better than Pythagorean, and four games below their actual record.
In projecting final standings, FanGraphs takes into account factors including schedule and changes in player performance. Several White Sox, notably Alexei Ramirez and Melky Cabrera, had first-halves that were far off career performance. Expectations for late-season finishes closer to career norms lead to a team projection of 24-23 the rest of the way, with a 5.6 percent chance of making the playoffs.
The Cubs’ projection is 25-21 the rest of the way, a .541 percentage that’s nearly the same as their .543 BaseRuns standing. But that, according to the projections, should be good enough to get to the postseason. The Cubs are listed with an 88.1 percent chance of making the playoffs, broken down to a 5.4 percent chance of winning the division and 82.7 percent chance of a wild-card berth. Even if Pythagorean and BaseRuns alike suggest the Cubs aren’t quite as good as their record, the projections are showing the team as good enough.