It is hard to separate Bradley and Carroll. All I know is, there are problems with how our defense has been handled. Maybe it's Carroll's fault. Maybe it's Bradley's fault. Carroll isn't going anywhere. He's just way too valuable as a visionary, evaluator, motivator, and developer. With Gus leaving, at least we get a 50/50 shot of replacing the one responsible for those problems. If Bradley was holding us back, this is a great move. If Carroll was the one holding us back, then we held serve.
I wasn't impressed with Bradley in 2009. You might recall that he and Mora implemented arguably the very worst pass defense in the history of our franchise. Carroll has turned crappy coaches into valuable collaborators (Nick Holt). That is a reasonable reason to suspect Bradley (who we are told is the one who made the play calls). Maybe Bradley's not the problem. Maybe he is. Either way, taking a 50/50 chance of fixing that problem with no downside is a good thing if you ask me.
There was almost no upside to moving Bevell. He got better as the year went on, and his style, his flexibility, and his college offense mentality seems like such a great fit for Wilson. Wilson seemed rather emphatic that he wanted Bevell to stay. Maybe you could chalk that up to "what else would he say." But if a friend of mine was up for a big job promotion, and I wanted him to turn it down so that we could stay together, I think at the very least that's a major endorsement of how much I like working with him.
The last thing I'll mention: I thought offensive play calling cost us really just one game this year- the Miami game. But even in that game, the offense hurt us less than the defense did. There were probably 4-5 games Seattle lost this year where defensive philosophy and playcalling played a major role in those losses. So to me, I would have viewed offense in a more positive light than our defense this season, despite our defense finishing #1 in scoring.