Right. You compared the leaving of James to the leaving of Givens. Go back and read what you wrote. James. Givens. If all you were doing is comapring the loss of a player to FA, why didn't you use Matt Chatham? Anser: Because you don't equate the loss of Chatham to James, only the loss of Givens.
Anyway, no one has minimized the impact of Givens. He was a good player. He sucked his first year, but came on. For a seventh round pick he was magnificent. But he isn't the guy who will make or break a team. He just isn't.
Givens will be missed, but not as much as Ted Washington, or Lawyer Milloy, or ....
What happens is the Opposite of what you are saying. Doomsayers attribute magical qualities to every player that leaves the Pats, and believes that every new player coming in is a stiff.
Some people would complain if they were hung with a new rope.