Joe Brady's one of the best in the biz. Daboll was very good too.
If someone has the opinion that Allen is the better QB, that's fine, and you can make a decent argument for it...but the idea that Mahomes has had everything a QB could ask for just isn't accurate. He's basically never been supported by a good running game, tackle play has been mediocre/poor for several years, his top receivers have been either weak or injured in recent years, the defense has been mediocre or bad more often than not in his career, and he had the worst LT situation in the league last year.