Seems like teams pick running backs based more to add a specific element to their offense than merely because they lack a bellcow, so evaluating prospects is a little different. Players who might've been more highly valued 5 or 10 years ago because they could handle a large workload are less valuable than a more gimmicky player, because a workhorse back who gets it 10 yards a game is probably only getting you 40 yards. You're hoping the gimmicky back can get you those 40 on 5 touches. I don't mean "gimmicky" in a derogatory way.
But my thought is that evaluating running backs isn't comparing one to another and asking which is a better "starting running back," because unless you're really elite that position is going on extinct. Anymore it's just a question of what a player offers, and then projecting which skills are going to be viable assets in the NFL.
I haven't been watching or following Texas A&M this year, but I watched quite a lot of them last year evaluating Tannehill and so I've seen a lot of Christine Michael. At this point he's probably the no. 1 senior running back for me, but not following the program, I don't really know why he's not producing so much this year. I think I heard something about a suspension towards the beginning of the season? Anyways, here's him having a (mostly) great game against Arkansas last year:
Senior, but relatively low mileage for a player who's started since he was a freshman with around 500 career carries. Listed at 5'11" 220.
Has the acceleration to run away from defenders. Has real suddenness about him. Doesn't make you want to call him a power runner, but runs with physicality. Shows a variety of elusive moves, regularly employing successful spins, stiffarms and showing the ability to break direct tackles. He tries to use every button on the controller, but he doesn't dance; he picks one and goes with it. His spin is pretty deadly because he sets it up like he's going to try and run you over, usually making contact, then immediately whips his momentum around, plants his foot and heads to open field.
Terrific balance, can regain it by sticking a hand on the ground and then rapidly accelerating again once reoriented. Looks like he could be valuable in the screen game.
Due to his running style, sometimes the ball is exposed. Will need to be more situationally aware and always carry it high and tight against his body running through traffic. Has a tendency to bring it away from his chest as his arms naturally want to pump when he runs. Runs with a little bit of abandon, which I think you want in a running back, but needs to work on the way he carries the ball.
Reminds me of what I liked about Doug Martin last year, although I'd say Christine Michael is a sleeker, faster version. Little more DeMarco Murray in him. Doug Martin seemed more well-rounded to me. I didn't see a lot of pass-blocking in Michael's game. I put him in the same range as I had Martin last year: Late 1st-2nd.