Hell no. Just because 1 running back is doing better than the other doesn't mean he's a better back.
I've seen them both play, there's no reason for me to believe that Johnson is better than Gurley. Sure Johnson is good, but as of right now, his success and Gurley's lack of it, is all circumstantial. Better run blocking and more threats on Az.
Lets just wait til the season ends before we make these crazy fantasy trade that probably would never happen.