It's like the guy with beer goggles at the bar ... he sees one nice looking girl next to two two less attractive but decent looking women and think she's pretty because all the other people say so. Not evaluating talent ... just going with the crowd.
Any good evaluator scored Justin Herbert as elite in terms of arm strength, size, mobility, character, and his only knock being inconsistency .... because he had a LOT of reps where he showed exceptional accuracy and judgement. Just sometimes his mechanics got sloppy or he played hero-ball. All that is typical of a younger player. His undeniable ceiling was sky high. Had he played at Alabama people would have been saying he was the greatest prospect in the last decade. Had he not gotten hurt in high school, he might have been recruited by Alabama. The kid always looked like a stud and budding young NFL star.
Winning .... that's what the NFL is all about. Either you have masterful coaching with air-tight players playing mistake-free ball to execute the great coach's vision, just like the Dolphins and Chargers defenses did for Bill Arnsparger, or you build a team around great players, like the current Chiefs have done around Patrick Mahomes or the Buccaneers for Tom Shady. Coach Flo is no Arnsparger, thus Tua simply isn't good enough. Grier needed to get Herbert or find a new coach.