Earlier this month Football Outsiders published an analysis of rookie running backs in the preseason. In a nutshell, rookie backs who carried more than 25 times and averaged more than 3.94 yards/carry in preseason went on to average 4.43 yards/carry in the regular season. Backs that averaged less than 3.94 yards/carry in the preseason went on to average 3.5 yards/carry.
Taken together, this leads to the conclusion that our own Stevie Slaton could well become a good rusher in this league. It is also worth noting that the Greatest Running Back Of All Timez is bringing the average down, not up.
Slaton has certainly looked the part in preseason and Football Outsiders seems to think that, in this case, you can tell something about how a player will do in the regular season from their preseason performance.