I think this has less to do with moving KG to PF as it does with having someone else who actually plays defense on the court. If they had a defensive oriented PF, they would have gladly kept KG at center, but clearly Doc was fed up with the softness of the other big men defensively.
True that. KG is a constant, not the variable. C, PF, who cares? We're talking about a guy that played point forward throughout his career. He can adjust.
Bass is a decent man to man defender and a bad help defender.
Wilcox is an average man to man defender and a bad help defender.
Sullinger is an average (barely) man to man defender and one of the worst help defenders in the league.
And none of them can protect the rim at 6'8" or block a shot, which is coincidentally the only part of defense that KG doesn't do.