The Patriots leaned heavily on BenJarvus Green-Ellis as 61 snaps is an extremely high total. Part of the reason the number was so high is that Green-Ellis, in addition to his regular duties, played Danny Woodhead's role in passing situations.
That reflects the coaching staff's view that he's most reliable protecting Tom Brady among the team's healthy backs.
Ridley was a nice pickup last week, but the Pats RB game plan is always unpredictable. It seems like the team trusts Green-Ellis right now, and for good reason, young RBs often struggle in pass protection and Ridley seems to be no exception. Ridley's days are coming, but for now it seems like he's going to be a risky, unpredictable start.