I'm not sure what your definition of used to seeing seeing playing time is but I don't think it applies to any of these guys on the roster now (I don't count Blount as I think they are looking to let him walk).
White = 73 carries over three years
Burkhead = 87 carries over three years
Lewis = 149 carries over five years
Bolden = 203 carries over five years
Gillislee would add a whopping 154 carries over three years
More than just carries its receptions too. Plus most teams only carry 3 RB's or 4 Top's. Either it takes 2 guys to replace Blount or he is just signing guys for the sake of signing them now and will cut them in camp. If he signs Gilesee and gives up a pick for him then you would have to believe he and Burkhead won't get cut. Lewis and White probably aren't getting cut. There is 4 there without a fullback who if they carry one would probably knock a RB off that list.