You can tell that NFL free agency is winding down when the players being signed are being designated up front as backups. Two notable moves were Back to the Future transactions. Quarterback Trent Green, 37, returned to St. Louis to be the Rams' backup quarterback behind Marc Bulger and running back Warrick Dunn returns to Tampa Bay, where he began his career. Dunn will also be a backup -- at least on the depth chart -- to Carnell "Cadillac" Williams.

The guess at this early stage is that Dunn, 33, will have the bigger impact on his team for a couple of reasons. Assuming Bulger stays healthy, and certainly that's a big assumption in the NFL, Green will hold a clipboard all season and even if he gets to play, it's hard to see Green having much of an impact on St. Louis' playoff chances after a 3-13 season in 2007. However, in Tampa Bay, the Buccaneers should continue to be in the playoff hunt but need depth at running back where Williams has missed 16 of the last 20 games and is recovering from serious knee surgery. It's hard to tell whether Williams will ever be the same back that started his career with three straight 100-yard games but even with a healthy Williams, Dunn would be a change-of-pace back who can still add a dimension of quickness to an offense.