Gotta be IT4. Right now, he strikes me as a regular season allstar. But once the defense hones in on him, he can be stopped effectively. He's gotta prove that he can take it up another level once the playoffs begin, much like many stars in this league do come playoff time.
This.
You could say that about almost anyone who's not a transcendent (like LeBron, Durant, etc.) talent. Especially on a team that lacks other offensive focal points like ours does. Defense is stronger in the playoffs, and for a guy with IT's limitations a lack of offensive help makes it EXTREMELY hard for him to be the AS caliber player he was this year.
The fact that IT led this team to 48 wins and made the ASG is testament enough to his abilities. Put a guy like KD, Butler, Love, etc., who can shoulder some of the planking duties and it wouldn't be much of a problem. Paul George is a better player than IT, but chances are defenses will hone in on him and his lack of secondary options will bring them down. Does that mean PG isn't a incredible player? Of course not.