Randy Moss couldn't run a route all that well, but he did alright for himself. Burress runs this thing that some call a route, but it more like he just runs up the field and jumps for the ball. Assuming Johnson can't run a route to save his life, his athleticism alone will make him an average receiver (assuming he has a decent QB).
I might be going out on a limb, but I think CJ is athletic enough to run an accurate route. Lets be honest, some of the best route runners are a bit shorter and don't have quite the vertical leap as CJ does. Lets not expect the guy to be cutting rug like he was Marvin Harrison when the guy is more in the mold of TO, Moss, Burress and/or David Boston.
If CJ is a guaranteed bust, I would be fearful of taking any wide out in this class. Writers need to find something better to write about than make crap predictions that they will never own up to in the future.