In most competitive sports, Cycling being one, once you move up to the next level you can no longer compete at a lower level. I think that is how it should be with Nascar. I think Nascar is afraid of making that a rule because they fear losing a fan base that come because of the Cup drivers. I compare that to allowing a Pro football/basketball player to go back and play for his old college team when it fits his fancy. I look at it as a progression from the Small tracks to ARCA to Nationwide to Cup. It isn't really fair for the guys coming up to have one of the spots taken by a guy that has moved up to the next level. IMO