Yeah, i like the idea of there being a very specific REASON for blowing the dunk that is made apparent to the user...as opposed to how it is now where you just miss and wonder why it missed. sometimes you'll blow a dunk, then another time you'll do a similar dunk in similar situation and finish it...so why did one miss and the other go in? i wish there were more clear cut rules/explanations for makes and misses.
i also like the idea of there being a limit to how many times you can successfully execute certain "overpowered" moves (like dunks in traffic, turn-around fade aways, etc.). this would force people to be conservative about when they use certain moves so they could save them for when they really need them. if a user tries to abuse these moves too often, the player would start to miss these attempts. i'm sure there is a mild version of this already built into the game, but it might be nice for there to be a clearly communicated limit so you know when you've used something too much for it to be successful (almost like the Tony Hawk games where the more you repeat a certain move the less points you get for it). for example, if a guy keeps using the turn-around fade-away with Kobe, after the 4th or 5th attempt within a certain time frame, it will be impossible for Kobe to make the shot again within that time frame - this would force people to mix up their attack and try different things with different players. variety would be rewarded and repetition would be punished.