I don't see Miller having a significantly better season than last year. He might do a bit better, but he doesn't have the power or the vision to be one of the league's upper tier RBs. His numbers are already OK, I see more OK in his future.
The Earl Mitchell one is mostly speculation, as he'll be playing in a new team, new coaches, new defensive formation, different gap assignments and he'll be rotating with Odrick and Starks. So anyone who believes he/she can predict in advance that Mitchell will personally have a much better year than last season is reaching.
Never hear Mitchell mentioned in the OTA reports and he's played every snap with the first team defense. Would be good to get a sense of how he's faring.