Keep in mind Swift has been battling an injury (groin?) most/all season. He looks to be rounding into form the last game or two.
And yes, I think we'll continue to see more of Cook as the season goes. He's still a True Fr after all, and still has some things to learn, such as blitz pick ups, etc. But the dude can scoot. Let Swift/Holyfield/Herrien wear 'em down, then Cook run 'em ragged.