The whole team management thing is beyond any of us because we do not have all the inside info. I have confidence in Ainge.
As far as what happens if Shaq gets hurt , well its then time for garnet to be supoerman or we lose to LA again. Its very hard to plan around losing a top player. Suppose King Lebron goes down , there is no bench player to replace him.
The Celtics have always had a plan to win it all that involved some key , older , more fragile guys doing the job at crunch time. Bill Walton was the classic off the bench superstar. For two minutes he was the best center in the league , maybe ever. However beyond 2 minutes he was just too old and fragile by the time the Celts got him. The strategy to have him on the court for the last 2 critical minutes won them a championship. I think that is the same idea with Shaq. Now they do play more than 2 minutes to help give guys a rest but the key is to keep the game close and seal the win with the big talent , short minute old timers.
So the answer is , if shack goes down in game 6 , its unlikely we will win game 7. However , its the Celtics , never count them out!
