Some people continue to say Newcombe wasn't the same after his knee injury, but I don't think there's much truth to that.
After his knee injury:
Also after his knee injury, a school record 94-yard punt return (at 1:40):
Newcombe was elusive, fast, and a better passer than Crouch. He also was better on the option pitch. However, Crouch was also elusive and fast, and he was a more physical runner than Newcombe.
Maybe the difference was that Newcombe loved playing football, while Crouch loved playing quarterback.