No doubt big is better, if the talent is there.... so I don't doubt that at all. But small players can play, and play well.... IF they get the chance.
Now I'm not referring to Tutu here because Tutu is VERY small... but in general....
If a player doesn't meet size minimums he isn't ABOUT to get the same chance as someone who does... ONLY if he's extraordinary at some specific aspect.... like clocking a 4.25 40.
Once a player graduates HS size is by far the predominate requirement. For good reason? Yeah, I think so, most of the time... but I do not think it's definitive.