dual threat qb drastically opens things up in the rushing game for the RB, this isn't even a debatable issue. A very large portion of Taysom's rushing yardage came from scrambling out of the pocket during passing plays. Jamaal had roughly 25 less carries than Harvey, which is a normal variation per year if you just consider Harvey's carry stat progression. So what ever negative impact if any that Taysom had on the number of carries for Jamaal is completely out balanced by the fact that defenses had to hone in on Taysom's home run potential running ability.
What bugs me is that you made an analysis not to determine who the best overall RB is, it seems from your analysis that Jamaal was the predetermined best running back and you chose and ignored strengths and weaknesses and circumstances to make your argument.