Doc wants greater balance size wise, so the plan is to have KG and Bass start and then when KG goes to the bench, Collins will come in for him. To be quite honest, every minute that Jason Collins plays is a minute that the C's are doing the opposing team a solid. I do agree with Doc's decision to continue to keep KG's workload diminished in the regular season. Two things this team has going for it in the long run are that KG can play more minutes in the playoffs and that Playoffs Rondo is a better player than Regular Season Rondo.
Related: The Celtics are the worst team in the NBA when Kevin Garnett is on the bench