Look, to be fair (and I hope I don't get accused of coddling) Keegan has only shrunk as a scorer. In every other way he's continued to improve and he has continued to step up big-time both as an individual/team defender and as a rebounder. He's also improved as a playmaker while maintaining a turnover rate which is among the best in the league for high minute players. Obviously we'd love for him to return to college form as a high volume scorer in addition to all of that but we're less than 1/4 of the way through his 3rd season and until very recently he's been the 4th (and sometimes 5th, when Monk is rolling) option on the floor... so a bit of leeway in adjusting to his changing role seems warranted.
His aggressiveness as a scorer does go up when he sees the ball go in the net so maybe the solution here is to run more plays for him early in the game?