NE isn't stupid, everyone vastly overrates Welker and NE wasn't going to pay big $ for a player like that. This is the team that knows him better than any other and they signed a new player to more than they offered Welker and were ok letting him go to a team they will be competing w/ for a SB berth next year. That should tell us something.
New England isn't perfect, and belichek ain't god (seen their drafts over the last decade?). They screwed up on this one.