Musky had a nice debut. I was interested to see how they used him. It is just one game and Horford didn't play, but this is how he was used:
Muscala + Griffin 8.5 min +5
Muscala + RWIII 7.2 min +0
This, along with how things looked on the court, it appears he is more PF than C. He can probably play both but we have fewer options at PF right now. I think pretty much all he bigs can play center, maybe center is a bit of a stretch for Grant, but we have a lot of center options.
This is how I see the bigs:
Horford Starting PF, Back up C
RWill Center Only
Kornet Center Only
Grant Mostly PF, a little C
Griffin Mostly C, a little PF
Muscala Probably mostly PF, some C
In general, I think it is better if starters have a clear natural position. With bench players, it is useful to have versatility. To me, RWill (C), Grant (PF), and Kornet (C) have clear natural positions but the rest don't. Horford is the starter without a clear natural position. He is so experienced that it doesn't seem to matter. He can play starter level at either position, which is rare.