You're right, they didn't get there by playing poorly but if you think that makes him above criticism, then we are just going to have to disagree. Also, let's not act like SF was an offensive juggernaut and that's what even got them to the SB. It was their defense.
And no, IMO he hasn't shown he knows how to utilize the talent he's been given, which is why he was fired.
EDIT: they had a problem getting in plays on time all that season. Point is it followed them to the SB and it followed Roman here to Buffalo. The guy is not without his faults.