Ruth's 1920 slugging

[brett]

I noticed that Ruth's 1920 slugging mark was returned to .847. For a coupel of years it was shown as .849 and I thought it was adjusted about the time that Lajoie's average was raised from .422 to .426 and Wilson's RBI to 191, Cobb's hits to 4189. What caused the revision back to .847?

[Ubiquitous]

His record was missing an at bat for 1920. He was originally credited with 457 at bats but that has been revised on the internet to 458 at bats. The game in question was on May 15th.