Turner is extending a lot more on his follow through in that video posted earlier in this thread. That does two things:
1.) It makes touch more consistent because the farther the forearm moves forward, it has more of a factor in overall touch. With Turner's shot last year, his touch was based mostly on his wrist flick and triceps. It wasn't a good combination. It's more fluid because now he's recruiting his forearm as well.
2.) It increase his arc. Last year, his forearm was almost vertical at his setpoint and on his follow through. His elbow would go up and his wrist would go forward. This is awful for arc, and was one of the biggest reasons he struggled from range. The ball would be pushed off of his hand due to the flick of his wrist straight forward. However, if he's extending his forearm forward now, it'll increase his arc. It only looked like a 1 or 2 degree difference in entry angle to the basket in the video earlier, but that's a big difference. If his forearm is extending more forward, it'll push his hand through the ball, rolling the ball from his hand, up onto the very tips of his fingers, and will roll it off of the top of the hand, giving it more arc and touch.
Basically, his shot was a "flick" last year, because he didn't extend his forearm on his shot. If he fixes that, I expect his shooting to improve dramatically, as he has good form in terms of release timing, his elbow in on his set point as well as a straight hip/elbow/forearm/hand placement on the point of release.