On first down, if we run the ball, we average about 4 yds. This is misleading a bit though because the distribution is not normal. The most common outcome is a gain of 1. With passing, the average is 9 yds and most common is 0 yds.
When on defense, if the opponent runs the ball, they average about 6 yds, the most common outcome is a gain of 5. If they pass, they average about 4 yd, the most common is 0 yds.