I checked his split stats when we signed him. He wasn't terribly effective as a short yardage back, no more than the average RB. As to why couldn't he learn? I don't know, but he's 31, has never really done it in his career, just doesn't seem to make much sense to try. I may be wrong, but really, we need to use DiMarco more in that role. He played well against Miami, don't recall him being used as much all season until last week.