My defenses play my RB's.. Who to start and sit?

[gjperez78]

I'm in an ESPN standard league. MY RB's are Lesean McCoy, DeMarco Murray, Ryan Mathews, Michael Bush. My Defense's are Atlanta and Arizona. I was at the Monday night game (Atlanta vs. Denver) and I picked up Atlanta's defense because they looked really good and I think they are highly under rated. I don't think it's a good idea to start a RB and a defense that are playing each other so I'm tossing between starting Atlanta and sitting Mathews or starting Arizona and (I can't believe I'm even considering this) sitting McCoy. Any thoughts?

[Walbridge20]

start arizona and sit matthews

NEVER sit McCoy

[gjperez78]

that's what I was gonna do originally but starting a defense that plays my RB just seems like a bad idea. I suppose both could have a good day but.... I just don't know. I'll probably wind up doing that though. Thanks