would be an upgrade for the QB position?

Are you not concerned about durability given his slight frame and small size for a college QB?

I see arm strength, but can't compare it to other QBs as college seems to have a lot of strong armed QBs, but not many accurate and quick processors. We learned about Zach in the pros, success is determined by the ability to quickly make the right read to avoid the pass rush. That same issue exists in college and can be mitigated if you have a dominant O Line, which BYU can have from time to time.