We can always go platoon at the pf.
I'll make a fearless prediction: Assuming he stays healthy, Koufos will start every game this year. I will also predict he has a better season than last. His numbers were respectable, but the pace was too fast for him, and he missed too many bunnies. The slower place will improve his efficiency, and he's in superior shape with body fat around 5-6%. The superior conditioning will help him get to his sweet spots, defend vertically, and attack the boards.
Koufos aside Boogie works by process of elimination too. Willie is not ready to start. Tolliver has never been a starter. Omri has not proven to be a starter, either at SF or PF. Rudy is entrenched at SF if he's not traded. Barnes can play PF but he's more of bench spark. It would be nice if Willie built on his rookie season and made compelling case to start, but his rebounding and scoring leave more to be desired. He's too unsure of himself and feeling his way. This has to give Joerger pause.
The biggest variable of all though is giving Boogie assistance down low so he's not always the last line of resistance on defense. And so he can be moved off the toughest match-up down low to avoid early fouls. Let Koufos pick up some of this responsibility, so Boogie is fresh for crunch time.
The counterargument is there is not enough mobility between Boogie and Koufos to defend on perimeter. One, let the opposition play small and lets see them match up with us. Two, Joerger asks the big to show on pick and roll to give time for guard to get over the pick. He's not asking for his big to switch onto smaller offensive player. Showing and rotating back is what is required. Both Koufos and Cousins have gotten themselves into good enough condition to do this.
The other counterargument is Koufos does not give us scoring compared to Omri or Tolliver. This is true but with Affalo, Rudy, Cousins, our 1st, 2nd and 3rd scoring options are set. We need dirty work, hustle, rebounds, interior defense, smart play from other starter, not more points. I can't say with 100% certainty this is how it will play out, but I am fairly confident this is Joerger's general thought process.