Is Ingram still playing on his rookie contract? If so could it be that the coaching staff is just trying to get their money's worth with no real intention of keeping him around once the contract expires?

I'm also in the camp that says Ingram can't hold Pierre's jock, and Pierre should be getting the lion's share of the carries. But if Ingram is playing-out a contract that won't be renewed, we may as well use him as the battering ram and keep Pierre fresh.

In other words, play Pierre as much as is required to win the game. If he can't find running lanes, then Ingram surely won't.