Once Dedmon started to learn how to play Defense without fouling, I was excited about the possibilities, thus am happy to see Pop is starting him and that Pau is embracing his new role with the team. As others have already mentioned, Pau fits best better with the second unit and Dedmon with the first.
My favorite reason is that of defense, Pau and Tony can't be on the floor together for long stretches of time against offensive juggernauts like the Warriors or the Rockets. And let me say that both of them have elevated their play on defense since the all star break.