As someone who lives in the area and watches the Big 12.. I don't think he will ever be an every-down back.
He reminds me of Dante Hall, if any of you remember, he was a running back at Texas A&M and we drafted him as such. The general feeling before he broke out as a kick returner was that he was pretty mucha bust, though.
I can see Sproles as an explosive returner and someone who could have a role in an NFL offense, but... the guy is a midget.