Football Outsiders

DVOA (Defense-adjusted Value Over Average) calculates a team's success based on the down-and-distance of each play during the season, then calculates how much more or less successful each team is compared to the league average. According to Football Outsiders, DVOA "breaks down every single play of the NFL season to see how much success offensive players achieved in each specific situation compared to the league average in that situation, adjusted for the strength of the opponent. ... Football has one objective -- to get to the end zone -- and two ways to achieve that, by gaining yards and getting first downs. These two goals need to be balanced to determine a player's value or a team's performance."[3]

There is a separate DVOA measurement for special teams, which "compare[s] each kick or punt to the league average for based on the point value of field position at the position of each kick, catch, and return." [4]

DYAR (Defense-adjusted Yards Above Replacement) calculates each player's cumulative value above or below a "replacement-level" alternative. DYAR differs from DVOA in calculating a player's total value through the course of a year, and not on a play-for-play rate. States Football Outsiders, "DVOA, by virtue of being a percentage or rate statistic, doesn’t take into account the cumulative value of having a player producing at a league-median level over the course of an above-average number of plays. By definition, a median level of performance is better than that provided by half of the league and the ability to maintain that level of performance while carrying a heavy work load is very valuable indeed."[5]

Adjusted Line Yards (ALY) "differentiate[s] between the contribution of the running back and the contribution of the offensive line." ALY attempts to "separate the effect that the running back has on a particular play from the effect of the offensive line (and other offensive blockers) and the effect of the defense. ... Yardage ends up falling into roughly the following combinations: Losses, 0-4 yards, 5-10 yards, and 11+ yards. In general, the offensive line is 20% more responsible for lost yardage than it is for yardage gained up to four yards, but 50% less responsible for yardage gained from 5-10 yards, and not responsible for yardage past that. Thus, the creation of Adjusted Line Yards."[6]

Drive Stats calculate a team's average success rate on a possession-by-possession basis: "[E]ach team's total number of drives as well as average yards per drive, points per drive, touchdowns per drive, punts per drive, and turnovers per drive, interceptions per drive, and fumbles lost per drive. LOS/Drive represents average starting field position (line of scrimmage) per drive from the offensive point of view. Drive stats are given for offense and defense, with NET representing simply offense minus defense."[7]

Another metric Football Outsiders uses is Pythagorean projection, which estimates wins in a season by a formula originally conceived by baseball analyst Bill James, that takes the square of team points, and divides it by the sum of the squares of team points scored and allowed.

The 2011 edition of Football Outsiders Almanac[8] states, "From 1988 through 2004, 11 of 16 Super Bowls were won by the team that led the NFL in Pythagorean wins, while only seven were won by the team with the most actual victories. Super Bowl champions that led the league in Pythagorean wins but not actual wins include the 2004 Patriots, 2000 Ravens, 1999 Rams and 1997 Broncos."

Although Football Outsiders Almanac acknowledges that the formula had been less-successful in picking Super Bowl participants from 2005-2008, it reasserted itself in 2009 and 2010.

Furthermore, "[t]he Pythagorean projection is also still a valuable predictor of year-to-year improvement. Teams that win a minimum of one full game more than their Pythagorean projection tend to regress the following year; teams that win a minimum of one full game less than their Pythagoerean projection tend to improve the following year, particularly if they were at or above .500 despite their underachieving. For example, the 2008 New Orleans Saints went 8-8 despite 9.5 Pythagorean wins, hinting at the improvement that came with the next year's championship season."