Another small tidbit is the source of the data. 82games is using play-by-play data and Knickerblogger, at least in season, may be getting the data from
Doug's Stats, for instance. Basketball-Reference uses the Lahman dB (I think.)
Aaron Barzilai's
site has up-to-date play-by-play data for download. He also has the play-by-play back to the 2005-06 season.
BTW, Justin Kubatko (Basketball-Reference) plans to offer updated in-season stats starting some time in December. Here is a sample of the proposed new layout.
Player Page
Team Page