I hope you have another QB. If it's for your back-up, what bye week is your starter? If it's late enough, might as well wait and see. And I would hold onto Knox. Some of those you listed may end up consistently outscoring Knox, but I wouldn't do somehting based on 1 week.
12 Team League. We start 2 QBs and get .5 PPR, otherwise standard scoring
QBs: Stafford, Fitzpatrick, Collins
RBs: Charles, Mendenhall, Best, Starks, Carter, Karim
WRs: D. Jackson, Marshall, S. Smith, Green,
TE: Hernandez, Cook