His TS% was actually down a bit this year under D'Antoni. This year Lee and Tyrus both shot around 35% on jump shots. Neither player is a good shooter, the two differences between them was that Lee took a lower percentage of his shots as jumpers, and is also a much better finisher on his layups.
I don't really expect much more than what we've seen out of Tyrus, most players who have gotten minutes don't improve significantly after their third year. He might get a little better.
As I said in my first post in this thread, I don't think Lee will sign for a reasonable deal, and will take the QO. If he decides he wants long term security and was willing to sign for a bit more than the MLE then he'd be a good pickup. This is assuming we miss out on Bosh/Amare/West. If you can't get a star, all you can do is try to put the best team you can together.