Well I just look at it as he is behind Turbin and Lynch, was a 2nd round pick, has not been able to break thru, Lynch is going to get his rest and not do a lot of contact until the last few weeks of training camp and some limited game time, so playing him looks to make sense. Turbin is coming of a hip injury and they are going to limit him also. They have fodder to run drills with and Michael.
Getting anything for him and there is always a need for a RB at some point by a team, unexpected situations happen. Showing he can blow up pre season is a good way to market him at this point.