Plus or minus. He can essentially carry what a starter gives to the end of the game. Problem is, he is only useful every 5th day in that scenario. He can impact more games, maybe up to 3 games per 5 in a shorter role.
It will be harder to have him stay in this role once the roster size drops. Here is why. Let's say Cora decides he can be useful as a piggy back guy and targets Hill as his guy to piggy back with. Well, next Hill start, the sox score 10 runs and Hill is cruising. Why burn him then? Now you have him ready to piggy back on the next starter, but lets say the sox are either in the middle of a run or the middle of a losing streak. It is far harder to predict who will be starting than it will be who will take over in the 5th and carry it the distance