I agree with those who say it is strictly to help build chemistry with the starters. I also think that our "top rotation players" all need to build chemistry. With so many new players Doc has to experiment with lineups and will do so for the next couple months IMHO.
With KG, Paul, Rondo, and presumably Bass, he needs to see who is best suited to start at the SG. Maybe he sees Lee as a starter going forward and will use AB with Jet as an energizing backcourt for the second unit along with Green and Bass in the frontcourt.
Other than our current top three, I believe he is sending the message that no starting position is set in stone and he will change them to what he thinks is best for the team. The comments about starting Sullinger or Darko are in the same context for me.