Sounds like nothing more than an insurance move to add an extra RB with Moreno being out. As he didn't generate any buzz even in the preseason, tough to get excited about him.
you must not have paid attention the Bronco Camp thread
Admittedly, I did not, but the coaching staff obviously valued Lance Ball, who we have seen enough of, more than JJ. If you have any professional assessments, pass 'em along, please.

His preseason game logs looks very pedestrian ( though that can be said for the whole RB-squad ), and the fact that this is his 3rd team in his short career and nobody has even seen fit to give this guy a game jersey tells me that they've seen something(s) that the fantasy scouts who are high on him haven't. That said, one of those teams was Carolina, so it would be no small feat to leapfrog onto the gameday roster.
Anyway, I know Cecil is high on him, but what else do we have? If there's evidence suggesting I should boot Karim, Carter or Antonio Brown from my redraft roster, then I'm happy to.