Baseball by the numbers: Breaking down the White Sox’ BABiP in 2021

As offensive teams go, the 2021 White Sox were good but a level below the best.

The Sox averaged 4.91 runs per game, fifth in the American League behind the Astros (5.33), Rays (5.29), Blue Jays (5.22) and Red Sox (5.12). Their 190 home runs tied the Angels for 11th in the AL, but their .336 on-base percentage was second to the Astros’ .339 and pushed the Sox to fourth in OPS at .758.

One category the Sox led was batting average on balls in play, which excludes homers and strikeouts to weigh batted balls on which the defense has to make a play. The formula is (H - HR) / (AB - K - HR + SF).

The Sox’ .310 BABiP led the majors. The AL and major-league averages were .291, so the Sox picked up about 70 hits more than average when they put the ball in play, not counting the effect of getting more plate appearances with hits replacing outs. Tim Anderson gave his .309 batting average and .806 OPS a boost with a .372 BABiP to tie Starling Marte for the major-league lead.

BABiP isn’t as strongly associated with runs as on-base percentage, slugging percentage, OPS, weighted runs created plus or many other metrics are. You can have a high BABiP and score few runs. That happened with the Sox in 1991, when they led the AL with a .329 BABiP but ranked 13th at 4.4 runs per game.

A certain amount of good fortune goes into a high BABiP. Is a batted ball just within or just out of a fielder’s range? Chance will tell. Hitters who have a much higher or much lower than expected BABiP tend to regress toward the norm thereafter.

Speedy runners who can beat out infield hits get a BABiP boost. Averages have been declining on grounders, especially pulled grounders. But fast players who hit grounders to the opposite side have a chance at extra hits.

Anderson fills the bill. Data at Fangraphs.com shows his 2021 batted balls of 22.7% line drives, 55.3% grounders and 22% flies feeding into his .372 BABiP. Anderson has had BABiPs of .328 or higher in five of his six seasons. Only one of .289 in 2018 was below the league average. His highest, .399 in 2019, featured more balls in the air than on the ground, but that included his career-high 23.8% line drives among the flies.

Yoan Moncada, with a .350 BABiP last season, was exceptionally high at 26.6% liners with 43.8% grounders and 29.6% flies. Luis Robert, not a qualifier with only 296 plate appearances, soared to a .394 BABiP with more flies than grounders (26.4% line drives, 36.6% grounders and 37% flies).

The most likely scenario for 2022 has all three declining in BABiP but staying above the major-league average. The ZIPS projection at Fangraphs lists Anderson at .347 BABiP, Moncada at .337 and Robert at .336.

The Sox’ fate doesn’t rest with BABiP. There are bigger pieces of the puzzle. But extra hits don’t hurt.