Well it is part of the reason at least. Even before the opt-outs they had lost a lot of talent there. The op-outs put the nail in the coffin. Which kind of makes me wonder since the Patriot Way is all team first stuff why did so many guys bail out on them? Things that make you go hmm.
I think with Bill you need to give it a season or two. You need to give him time to find an ideal QB and rebuild a roster that was constantly in win now mode with an aging QB. Not that they made bad signings, I just mean they favor veteran players who complimented Brady who is a very unique QB in my opinion. In other words what worked for Brady in NE probably wont work quite as well for his replacement unless it's another elite QB. Brady on the other hand went to a team with pretty good weapons and so I think you can form some sort of opinion on him this season.
When you're already one of the oldest head coaches in NFL history, I imagine that its hard to start over.