Doc always has to be mindful of the balance between rest and practice time. Sounds like he's opting for rest after a back-to-back that included an overtime period. Probably a smart thing.
On the schedule: rest, holiday cheer - Boston Celtics Blog - ESPN Boston
With a three-day break in the schedule, Celtics coach Doc Rivers is sticking with a desire to maximize rest. While Boston players undoubtedly will be at the team's training facility over the next two days for treatment, workouts and light shooting, the team won't reconvene on the floor until Tuesday.
Rest. Doctor's orders.