With four weeks left in the regular season, the BCS championship picture is much clearer than it was a week ago, but there are still plenty of scenarios that could further change the way the 2013 season plays out.
No. 1 Alabama and No. 2 Florida State currently have a commanding lead in the race to reach the BCS title game, but don't forget that Bama was ranked fourth at this time last season and went on to win the championship. As long as there are games still to be played, crazy things can happen (also see 2007).
To get a better sense of how the BCS title game picture could unfold, let's look at the best- and worst-case scenarios for each of the BCS top-five teams during the final four weeks, assuming that each team wins all of its remaining games. Obviously, a team's worst-case scenario is to lose out and not be part of the BCS. This is really an attempt to focus on the things that are out of a team's control and gauge how many of those events would have to go the right way to help that team or the wrong way to hurt it.