The S&P+ Ratings are a college football ratings system derived from the play-by-play and drive data of all 800+ of a season's FBS college football games (and 140,000+ plays). There are three key components to the S&P+:
Success Rate: A common Football Outsiders tool used to measure efficiency by determining whether every play of a given game was successful or not. The terms of success in college football: 50 percent of necessary yardage on first down, 70 percent on second down, and 100 percent on third and fourth down.
EqPts Per Play (PPP): An explosiveness measure derived from determining the point value of every yard line (based on the expected number of points an offense could expect to score from that yard line) and, therefore, every play of a given game.
Drive Efficiency: As of February 2013, S&P+ also includes a drive-based aspect based on the field position a team creates and its average success at scoring or preventing the points expected based on that field position.
Opponent adjustments: Success Rate and PPP combine to form S&P, an OPS-like measure for football. Then each team's S&P output for a given category (Rushing/Passing on either Standard Downs or Passing Downs) is compared to the expected output based upon their opponents and their opponents' opponents. For the drive efficiency portion, the same approach is taken based on net points and starting field position. This is a schedule-based adjustment designed to reward tougher schedules and punish weaker ones.
The S&P+ figures used in the tables below only look at the plays that took place while a game was deemed competitive. Garbage-time plays and possessions have been filtered out of the calculations. The criteria for "garbage time" are as follows: a game is not within 28 points in the first quarter, 24 points in the second quarter, 21 points in the third quarter, or 16 points in the fourth quarter.
Also included below: a team's percentage of total points scored and its Adjusted Record. Based on single-game S&P+ performances, this is the record a team would have had playing a perfectly average team, with a perfectly average number of breaks, in each week of the season. Adj. Record gives you a different way to visualize the impact of both team consistency and schedule strength.