In all fairness, Zach's first half season with the Bulls was an unmitigated train wreck. He looked like a hot mess that had no business being on the court, let alone being worth 20M per. He only got matched because not matching would have made the FO look like utter fools, given that he was the main piece of the trade for Jimmy and that they had decided to make him the face of the franchise before he had even suited up for a single game. Back then, he sure did not deserve his contract and the Bulls took an awful risk ponying up that much for somebody who had just blown his knee, and looked like utter trash coming back from it... and all of that after already having the experience with Rose which had killed the team's contention chances.
It was a bad decision that kinda' worked out because they decided to invest in him and give him Hardenesque usage. He's a much better player now--that much is true, but that's a very low bar to clear, if we're talking first year with Bulls Zach. Zach has always been a phenom athlete and a good scorer, but going back to his Minny days, the coaches were saying that he's just a clueless player that just doesn't understand HOW to play outside of running, jumping and scoring.
He's matured some, true enough, and I think Jimbo's one redeeming quality as a coach seems to have been to coach some of the stupid out of Zach, but he still, to this day, CANNOT see the game in real time. There's no shame in that, BTW. Most guys in the NBA can't--it's just that if you are using up a third of your team's possessions and are the de facto lead ball handler, it would help the team quite a bit if he could.
I think Thibs had it right on how to use him--which was almost exclusively as a finisher of plays. He probably saw the same things--immensely talented, but cannot be trusted to make a good decision with the ball on a consistent basis, especially in tight games. I think a Zach that can play in a similar fashion to his last year in Minny, but more mature and at 19-21 ppg is much more valuable to a team than 25ppg Zach that utterly dominates the O. The last couple of years, his best games were really when he played mostly off-ball and did not have to dribble much--they were just circumstantial because the Bulls never made a consistent effort to use him that way--but to me, it's doable. That kind of Zach is worth more than 20M per, and probably worth his 25M extension. The one that kills the O with his ISO usage, not so much, no matter what the raw numbers say.
Somebody needs to explain it to him that as a shooter this good, every time he pulls up with a guy in his face is a suboptimal outcome, even if he makes it, given that he is pure money when left even remotely open. To me that's kind of obvious--Klay went from just another good young player to straight up elite once Kerr made him move around, rather than play mostly ISO like Mark Jackson had him do earlier.