Quite a big deal.
He returns quite a bit of depth to a runningback corps that will give us a bevy of options if nothing else. One of three seniors in the backfield, it wouldn't be a big surprise to see Bass starting at some point this year if Robinson cannot parlay some of his hot play from last year.
Bass fought through injury last year, and may have been our most complete "runner" last year in terms of power, speed (and nasty stiffarms). Robinson had a bit more elusiveness on his side and was a better target catching the ball.
I still don't completely trust Jason Scales to shoulder any sort of load, which is sad. The honest truth is that he might likely be the 5th most talented runningback on our roster. I think Bass has the most raw talent, with redshirt Bo Williams right there. Robinson has shown he can break out, while Jason Harris sits way back on the depth chart despite having flat-out speed, as well as being one of those "practice studs".
I had a feeling that we'd see about 70% Alexander Robinson if Bass did not return, but this really should result in more of a runningback by committee unless someone just breaks out. Chizik said he fulfilled all his requirements (getting his ass to class), so it's nothing but good news.