Vikings RB Adrian Peterson got most of the day off, with Matt Asiata and Jerick McKinnon getting most of the first-team work at running back. Asiata, to me, looks quicker through the holes than he was last year, when he averaged 3.8 yards on 44 carries. He could get some carries in relief of Peterson this year, and he's big enough to be a forceful downhill runner if he can do a better job of getting through the line with some speed this season.
It sounds like Asiata is the primary ballcarrier behind Peterson, with McKinnon taking on a pass-catching role. The duo would likely form a committee if something happened to Peterson.