I don't think Ray has to come off the bench. But, I wonder why it's that it's a delicate decision to make where the Spurs or Lakers could get away with making such a switch.
The thing about Ray playing with the second unit. Wouldn't he and House be in the back court. Then you'll have two shooters/scorers if Pruitt doesn't win the back up point guard duty. Someone should be the facilitator. Hence, why it might not work to have Ray come off the bench. If so, then Pruitt has to be the back up. Or Ray will need to look for teammates more than he would and turn down a few shots.
One of the biggest moves the Lakers make this season may not involve a trade or signing. They are considering bringing Lamar Odom off the bench in a role similar to Manu Ginobili who comes off the bench but plays a starter's minutes. This may be a very beneficial role for both Odom and the Lakers. I'd like to see the Celtics do something like that with Ray Allen, possibly starting Tony Allen. Tony always played better as a starter and it may help Ray to come off the bench with instant scoring.
http://celticsgreen.blogspot.com/2008/0 ... es_29.html