Actually, I don't think that's what anyone is saying. What everyone is saying is that if Losman is given a full year to start, and can do no better than 4-12, then we will know for sure that he is not the QB of our future. We can look for his replacement and move on.
But if Holcomb starts and goes 8-8, we still miss the playoffs, and we still have JP on the sideline with a big "what if" hanging over his forhead.