Shanahan is fine. His QB's since Elways departure have been Brian Griese, Gus Frerotte, Bubby Brister, and Jake Plummer. There's probably some others I'm forgetting but whatever, not a list that's going to get it done. Even then, the Broncos have had, what, one losing season since Elway left? Bellichick's a great coach... eh? What has he ever done without Brady? 36-44 in Cleveland.
If you look back and read what I've said, Coyer was the reason for the defenses collapse in my opinion. Teams found out how to move the ball on the Broncos defense and Coyer never made adjustments. There was a lot of games where the Broncos defense was great in the first half, and the other team would make adjustments and Coyer wouldn't and they got torched in the second half. He's a great teacher but he's a terrible play caller. There were times where he had Lynch playing in coverage and, I think, Sam Brandon blitzing and run stopping. Lynch is terrible in coverage and the strength of his game is blitzing and run stopping. There was a lot of flaws in his gameplan. He treated Darrent Williams like he was Champ Bailey and he put hm in positions to get beat. He played him eight yards off the line when all it takes is a double move to beat Darrent when he's playing that deep.
The team should be good with Cutler next year when he has an entire off-season to work with the first team.