Pro: The rankings are based on how a team performs and accounts for how many points they would be expected to score based on their statistical output such as rushing yards, passing yards, etc.  This ranking considers past seasons statistics with heavier weights placed on games that are more recent.  This ranking is the more predictive of the two.

Retro: This ranking only considers strength of schedule and the actual outcome of games in 2013.  This is a ranking of who actually has had the best season.

SOS: Is strength of schedule.