The Chicago Bears are set at the top two spots of the running back depth chart. New millionaire Matt Forte is arguably a top five tailback in the NFL and his new teammate Michael Bush is a starting quality back in his own right. I'm sure the Bears would like to save some mileage on Forte and give Bush a few touches here and there along with the majority of the short yardage situations. My guess is about a 65/35 split. But after these two, I believe the Bears are waiting for someone to step up their play. In my opinion the 3rd RB job is anybody's game.
Armando Allen was promoted to the active roster late last season and his 40 yards on 11 carries against the Packers made an instant impression. For a smaller guy (5'10" 190) he runs with a purpose. Allen is listed 4th on the depth chart along with veteran Lorenzo Booker who is on his 4th team since 2007. Of these three, only Allen could go back to the practice squad, but if he shows anything during preseason another team could claim him if the Bears try that route.
Harvey Unga was a supplemental draft choice of the Bears a couple years ago, but he's had a difficult go of it as a Pro. He was placed on the injured reserve as a rookie, then last year he left the team for personal reasons. He showed flashes of being a power back in past preseasons, but he'll have to really impress to stick around. The Bears have him working a bit at fullback, so if he can show something there and contribute on special teams, he may be a surprise addition to the final roster.
And speaking of fullbacks, the lone true fullback on the roster is Tyler Clutts, and his fate may be decided by the new offense. If Tice prefers his H-Backs, Clutts could be using his preseason snaps as an audition for the other 31 teams.
I'd expect the Bears to be active once teams start cutting players, both in looking for some potential practice squad depth and also for a possible upgrade for the bottom of the depth chart.