Kanter's been playing much better recently, but the stats you use aren't terribly convincing.
PER is absolute garbage. It's just a repackaging of boxscore stats, the accumulation of which require a player to have terminal possession of the ball (in almost all cases). Only one player has terminal possession of the ball, so PER ignores the contributions of 9 players on the court during a change in possession (or 8 for a turnover or when a basket is assisted), and ignores the contributions of all 10 players the rest of the time. Kanter's problems are in team play (mostly when he doesn;t have the ball): Positional defense, help defense, spacing, making quick reads/decisions/passes on offense, etc. These are all incredibly important aspects of basketball, but none of them are captured in the boxscore or, by extension, PER. Booker, on the other hand, has a pretty good feel for the game, and consistently makes good, quick decisions, and executes them well.
