The last time he played against men he got worked. He's dominated juniors,but the AHL is a BIG step up.
Remember how Quinn and Peterka looked their rookie year? They were in their D+2 seasons, too, and had a ton of growing pains. That's after Quinn had one of the best rookie season's in the AHL the year prior + Peterka was one of ROC's best players in the AHL.
3C is not an easy role to fill, and Savoie would likely have similar growing pains as Peterka and Quinn. This isn't the year to deal with growing pains at such a crucial position.
Savoie could impress in the AHL, be called up, and prove he's worth an NHL spot. Then, you have a good problem on your hands. On the contrary, we could gift him the 3rd line spot, he could struggle, and will be left with nothing to fill that spot. That's a bad problem to have.
I'm also not keen on having such a young center spine + top-4 D. Doesn't seem like a recipe to success, but I don't have any data to back that up.