It's not really comparable (fairly). It's not the RB's fault that Anae (and Hill as well) didn't use him. Unga was part of a long-time offensive set that used RB's so well out of the backfield with passing. That hasn't really been part of the game plan since this new offense came around. Both Hill and Anae neglect to involve him like they should.... And they should more this year. I expect it.
But otherwise it's not really fair to compare right now. Guys like Brown, Unga, and Di Luigi were all great out of the backfield with it because they were actually used. Jamaal was #2 as a freshman in receiving yards and they just didn't use him last year.
They're important, but lets wait until his career is all said and done, see how they continue to use him in this offense. Incredible shame if they don't this year.