Andy Dalton is PFF’s 2nd highest graded passer this season

Saint Spud said
The air yards stat was in response to him checking down.

But yes, QB rating is an objective metric. He’s 7th in the NFL.

https://www.statmuse.com/nfl/ask/nfl-qb-rating-leaders-2022

QB rating was invented in 1972, when only one QB achieved a 60% completion rating and no one had more than 216 yards/game. The game has evolved tremendously since then, I don’t think that stat has much relevance anymore.