No, Mendenhall is not that good. The packers running game isn't very good and rely on Rodgers. He is going to get better as the year goes on and Jennings gets back and WR adjust to the defenses that have been thrown their way. I agree that you would need to get a much better back that Mendenhall.
also depends on who your current RBs are. Are you going to get much of an upgrade?
Upgrade that running back and I would make that trade. That Packer offensive line still sucks and they have no rushing game, the Texans losing Brian Cushing is a big reason why Rodgers had a huge game last night.
Don't trade Rodgers, dude is a fantasy scoring machine.