There's some truth to this, but if you want to be a starter on a top defense or offense, I think you've got to follow Richard Sherman's advice:
"Great players stay on their side and do what they're supposed to do. How many guys have you seen switching from side to side on a No. 1 defense? You've never seen it. We're the No. 1 defense for a reason. Who coaches a No. 1 defense to be worse?" (
http://www.sportingnews.com/nfl/sto...romartie-response-criticism-seahawks-jets-cbs)
Versatile players can be valuable when injuries hit, or on special teams and every team needs a few of them. But great teams have great players at each position, for the most part.
Sherman is right, in my mind, about this: you want your elite, dominant players to be in positions where they can maximize their impact. You don't want Revis playing spy at the ILB spot of a defense, ever, for any reason.
But I'm not talking about Colledge or Wells as players of that ilk. Never in their careers were they considered one of the top impact players at their positions, and the question posed in this thread not only wondered where they went, but why they don't have jobs at the moment.
I think the discussion has pointed out two reasons: age (both guys have been around for eons in NFL terms, and age has caught up with them) and lack of versatility given where they would fit on a current NFL roster (since they really can only do one thing as players low on the depth chart, their greater salary hit, inability to play quality reps at multiple positions and the opportunity cost to develop younger players in keeping them).
No one is suggesting all players should do everything. I am saying that players who are not stars are smart to provide quality in more than one respect to empower teams to maximize their salary expenditures and roster flexibility.
As for great teams having great players at each position, I don't know that that statement holds water. The kid who made the game saving pick for the Patriots could hardly be considered great- no one knew who he was before that moment. I would agree that great teams typically have great players at IMPORTANT positions (QB especially, pass rusher, receiver, CB) and effective players at the others...