If you have a running qb or Adrian Peterson it's a lot. If you don't it probably does not change much. Those two things actually dictate coverage. The qb knows he is getting zone because if they play man it looks the packers on Saturday or OU in the cotton bowl. It was not by chance that ad ran for 210 and 199 against the pack. If you can run you will help your offensive line greatly. There are qbs that are so good that it does not matter if they have pressure or know the coverage (aaron rodgers) but it really helps most of the rest of them You are right tho there are no teams that running the ball 10% more efeciently is going to help vs passing 10% more efficiently.