Well yeah, that's the point I was making. Being fit overall requires the player to be available for the vast majority of games. Which I'm pretty confident he won't be.
I think we'll be able to manage both him and Carrick really well and get the best out of both of them. 60 for Carrick and 30 for BFS is a good start. I can see them being rotated nicely and it's an ideal situation.