Quincy Avery is a very respected QB coach who knows ball and is the personal QB coach for Deshaun Watson, Jalen Hurts, Justin Fields and Geno Smith. To compare him to Malik rosier as a QB coach is wild, Quincy's opinion holds weight to a lot of people. He's also the QB trainer for Air Noland who ended up choosing Ohio State over us last second.
Mario holding Herbert back isn't something that Oregon fans just made up, after Herberts rookie season there were a lot of people saying it and wondering why a QB like Herbert was throwing screens 25% of the time as a senior. Regardless at the end of the day it's just an opinion. Mario just needs to show QBs can thrive playing for him and that narrative will go away.