There's more to playing RB at this level than lining up behind QB and being handed the football and told to run like a jackrabbit... And at his size back then (and even now), he would NOT have held up for an entire season being heavily featured at RB.
They can't be on the field at the same time and you could def make a strong argument that all of them got underutilized. They all would be starters on any other team.
Onterio McCalebb gets a good chunk of carries with a similar build. But that's not really my point in all of this. They can't find a way to utilize him and it would be a shame to give a DB plays that would best utilize the skills Russell Shepard does offer.
TM7 is not going to be running the wildcat. He should be working on his man to man coverage in the offseason. All these stupid ass "what if" scenarios are wastes of time and thought.