LT,welker for Johnson(ten)?

i currently have LT and welker in a ppr league, and im being offered johnson RB from Ten, right now my running back situation is sketchy, i have coffee and choice and jackson, and obviously LT, WR i have s.smith(ny) johnson(hou) and marshall, plus welker and edwards on bench, would it be a good move, him losing johnson wouldn't hurt him at all he has peterson and jacobs, but at WR hes really week, ive been throwing rbs in and get decent points week to week, but not sure if it will work in long run, johnson had one hot week and the other weeks were mediocre WHAT TO DO?!?!?