It is the totally unscientific eye-test.
It seems to me that every time he tries to put the ball on the floor or create of the dribble, something bad happens - bad pass, turnover, etc... I think his release is slow, but it does not matter a lot, as I do not want him to shoot off the dribble.
On offense, I would like him to do what he does now - screen, spread the floor, cut aggressively if the D sleeps, pass to the next man if the shot is not there. That is pretty valuable as it is.
I do not think he has some dramatic improvement left in him. If he just continue doing what he already does just a little bit better, I'd be content. A short upfake and go would be great, just to keep the D on their heels. But that is more or less it.