This actually pertains to the entire Raps roster. There are a lot of people hoping that so-and-so develops such-and-such skill and so forth and so on. The stats in this article say they won't. Here are the two graphs:
Now, it's clear that what happens to the typical NBA player is that, over the course of 3 or 4 years, they refine their offensive skills until they peak, both as athletes, and as ball players. Then, there is an inevitable decline. Apply this to the Raps current roster and you've got Derozan, Gay, Johnson -- the whole roster except JV and T-Ross -- have peaked. This is what they are and there's no good reason to think they'll ever be anything else.
Incidentally, big men do not take longer to develop (this nonsense was something Colangelo used years ago to explain Bargnani's suckage), but point guards do.