good points, but think about why the other three QBs in that picture are not balked about being in consideration for the top QBs for BYU.
Heisman while at BYU (in line with your point) and Superbowl rings (contradicts your point, and yes they were phenomenal QBs while at BYU like too). They are considered some of the best because of the National admiration they brought for BYU, in a large part, because of their play in the NFL.
Zach can still cement a spot as one of the Greats by how he 'goes forth to serve'. For me, the jury is still deliberating.