Exactly, he spaces the floor better than almost anybody, and he's a crucial aspect of the game, and he was really good for us in the playoffs against the Heat.
And when you mention health issues, please keep in mind that it was just his ankle, which is easily correctable with the surgery to remove the bone spurs, and even then Ray was solid.
I'm really and truly not seeing O.J. Mayo being a suitable replacement for Ray if the Celtics want to win a championship this upcoming season. Ray is easily good for another 2 to 3 seasons. And, most important, when you're trying to go for a championship, you sure as hell don't make one of your principle opponents -- in this case the Miami Heat -- a much stronger team. That's what the Heat become if they get Ray on their team. Can you imagine us trying to deal with Lebron, Wade and Bosh with someone like Ray Allen spacing the floor for them? If the Celtics did not already have Ray Allen, we would be pursuing him hardcore, and everybody on this forum I think knows that.