This was one of the things bills fans wanted, speedy RB's to run the edges and those runs don't even work with Cook or Hines, so it's not the RB's fault here. Once they find something that works things could get interesting
I was looking at some highlights to see what the comparison was about and most of Cam's hits were behind the line or him sliding after a run followed by viscous helmet hits. Allen on the other hand goes one on one vs the defenders and then evaluates what he should do and usually ends up with the right move