Look at Petersen up at UW.
UW had 3 4* Qb's in the fold and Petersen didn't use any of them with success because they weren't the right guys to run his system of accurate throws and going through progressions. Cyler Myles retired from Football, Troy Williams is now at Utah, and Jeff LIndquist is a holder and TE now.
He went out and got Browning to run the system and it's worked out great.
Detmer was similar. The guy knew the offense inside and out and knew where everyone was going to be. Just an amazing college QB.