Click here for a glossary of general football terms.
If there is a term used at Football Outsiders you would like to see defined in this glossary, please email it to info-at-footballoutsiders.com.
Terms primarily used in our college football analysis, rather than our NFL analysis, are colored purple.
Adjusted Games Lost (AGL): Measurement of the cost of injuries, both in terms of missed games and games where players were not able to play to their full potential. Estimates a number of games based on whether players are listed as Probable, Questionable, Doubtful, or Out. Introduced in Pro Football Prospectus 2008 essay, "The Injury Effect."
Adjusted Line Yards (ALY): Statistic that attempts to, even to a small extent, separate the ability of a running back from the ability of the offensive line. Adjusted Line Yards begin as a measure of average rushing yards per play by running backs only, adjusted in the following way:
Each play is also adjusted based on game situation as well as quality of opponents faced. Adjusted Line Yards can be listed as total or broken down by direction to attempt to isolate ability of specific linemen. More here.
Adjusted Sack Rate (ASR)/Sack Rate: Sack Rate represents sacks divided by pass plays, which include passes, sacks, and aborted snaps. It is a better measure of pass blocking than total sacks because it takes into account how often an offense passes the ball. Adjusted Sack Rate adds adjustments for opponent quality, as well as down and distance (sacks are more common on third down, especially third-and-long). More here.
Aggressiveness Index: Jim Armstrong created this metric which measures how often a team goes for a first down in various fourth down situations, compared to the league average in those situations. It was introduced in Pro Football Prospectus 2006. The NFL average is represented by 1.0. A coach over 1.0 is more aggressive, and a coach under 1.0 is less aggressive.
ALEX: Air Less EXpected. Developed by Scott Kacsmar in 2015, ALEX measures the average difference between how far a quarterback threw a pass (air yards) and how many yards he needed for a first down. If a quarterback throws a pass 5 yards behind the line of scrimmage on third-and-15, that would be minus-20 ALEX. The best application of ALEX is to look at third and fourth down when it's really crucial to get 100 percent of the need yards to extend the drive. A high ALEX would be indicative of a quarterback who aggressively attacks the sticks, while a low ALEX is indicative of a conservative quarterback more likely to check down and/or rely on YAC. Yes, the name is inspired by Alex Smith, who frequently has one of the lowest ALEX averages in the league.
FO Angry Troll Mad Lib: Template created by reader zlionsfan to be used when fans who are unfamiliar with FO's statistical methods wish to complain about the placement of their favorite team in that week's FOXSports.com power rankings (based on DVOA). Reads as follows:
<team> is clearly ranked <too high/too low> because <reason unrelated to DVOA>. <subjective ranking system> is way better than this. <unrelated team-supporting or -denigrating comment, preferably with poor spelling and/or chat-acceptable spelling>
Catch rate: Percentage of passes intended for a specific receiver that are complete rather than incomplete or intercepted. Occasionally referred to as "catch percentage," but we prefer "catch rate" because it is shorter. Often shortened in stats tables to C%.
Catholic Match Girl: The girl featured in an advertisement that ran on FO during the 2006 season. Her fair face, doe eyes, and intense stare caused some FO readers to fall in love with her and others to run in fear.
Correlation Coefficient: A number between -1 and 1 that measures how closely two variables are related. The closer to -1 or 1, the stronger the relationship. A negative correlation means that as one value goes up, the other goes down (example: points allowed and wins). Values close to zero suggest no correlation between the two variables. (Note: while a strong correlation coefficient suggests that one variable affects another, correlation does not necessarily indicate causation.)
Curse of 370: The theory that a running back with 370 or more carries during the regular season will usually suffer either a major injury or loss of effectiveness the following year, unless he is named Eric Dickerson. Occasionally, the loss of effectiveness or injury takes place two years later (see: LaDainian Tomlinson, 2004). 370 carries is not a hard and fast rule, but a useful guideline to running back overuse. Introduced in Pro Football Forecast 2004, the 370-carry theory was expanded in Pro Football Prospectus 2006 to include any season with 390 carries in the regular season and postseason combined. Only carries count, not receptions. Read more here.
DAVE: This rating is used early in the year, combining early-season DVOA ratings with the preseason DVOA projection. (For first three weeks, it uses non-opponent-adjusted VOA ratings.) The goal is to get the best idea of how good a team will be over the entire season without jumping to conclusions based on one or two good or bad early games. The rating was created through regression analysis of week-to-week DVOA ratings from 2001-2005. It is called DAVE because of all the people who bug us about the complicated names of our stats -- a typical FO response was "well, we can't name the statistic DAVE." So this time, we did. Stands for DVOA Adjusted for Volatility Early.
Deep Zone: In the Football Outsiders system that breaks the field down into five zones, this represents when the offense has the ball from their own goal line to their own 20-yard line (in other words, the opposite of the Red Zone).
Defeats: The total number of plays by a defensive player that prevent the offense from gaining first down yardage on third or fourth down, stop the offense behind the line of scrimmage, or result in a turnover. "Plays" refers to tackles, passes defensed, fumbles forced, or interceptions. See Stops.
DPAR: Defense-adjusted Points Above Replacement. The method of measuring player performance used by Football Outsiders from 2003 through mid-2008, translating a player's value into an estimated total of points instead of yards.
DYAR: Defense-adjusted Yards Above Replacement. A Football Outsiders stat which compares the performance of each player, in terms of DVOA, to a replacement-level baseline rather than the league average for that position, then translates that total into yardage. Because DYAR is a total stat, not a rate stat, it helps show the importance of workhorse running backs and receivers who can draw the attention of the defense away from other players. DYAR replaced DPAR as our method for measuring individual players with the publication of Pro Football Prospectus 2008 in July 2008. The method and the computation of replacement level are discussed further here.
DSR: Drive Success Rate, or the percentage of time that a team will get a first down or touchdown in a given set of four downs. Introduced in the Pro Football Prospectus 2005 essay "Debunking the Myth of Drive Momentum" by Tim Gerheim and Jim Armstrong.
DVOA: The main statistic used on Football Outsiders, DVOA breaks down the entire season play-by-play, comparing success on each play to the league average based on a number of variables including down, distance, location on field, current score gap, quarter, and opponent quality. While it can be used as a measure of total team performance, it differs from other power ratings found throughout the Web because it can be broken down to analyze team effectiveness in any number of ways: down, quarter, rushing vs. receiving, location on field, passes to backs vs. passes to receivers, and so on. Read the article METHODS TO THE MADNESS for more information. DVOA stands for Defense-adjusted Value Over Average, although we use the same letters to refer to defensive rankings which are adjusted to take into account the quality of offensive opponents. When not adjusted for opponent, this stat is called VOA.
DVOA Era: Shorthand for 1991-2011, the seasons for which Football Outsiders has play-by-play breakdowns and therefore can produce DVOA and our other advanced stats. It is not meant to be as obnoxious as it sounds.
Effective Yards (EYds): This metric translates DVOA into a yards per attempt figure. This provides an easy comparison: in general, players with more Effective Yards than standard yards played better than standard stats would otherwise indicate, while players with fewer Effective Yards than standard yards played worse than standard stats would otherwise indicate. Effective Yards are not the best way to measure total value because they are more dependent on usage than DYAR.
Equivalent Points (EqPts): Method used by our college football analyst Bill Connelly, giving each yard line a point value based on the average number of points a team can expect to score from that spot on the field. (This is similar to the method we use to measure NFL special teams.) From there, each gain or loss is given a point value based on the change in EqPts.
Estimated wins: The number of games that team should have won if it faced an average schedule of opponents and average luck, as determined by the Forest Index.
Fantasy points: Scoring for a fantasy football league. While each league has its own scoring system, articles on Football Outsiders which reference fantasy football will use this fairly standard scoring system unless otherwise indicated:
Field Position Rate: Compares the number of plays one team ran in opposing field position to the number of plays the other team ran in opposing field position. These two numbers must add up to 100 percent.
Football Outsiders Almanac: Since 2009, the annual book written by the staff of Football Outsiders. Includes essays on every team, statistical tables, new research, and KUBIAK fantasy football projections plus advanced FO stats and player comments for "skill players." Replaced Pro Football Prospectus, which ran from 2005 to 2008.
Forest Index: A response to a claim that total team DVOA rankings "missed the forest for the trees," the forest index (developed near the end of 2003) spits out an estimate of wins based on a formula that combines DVOA ratings in offense, defense, and special teams, as well as red zone defense, offense and defense in the second half of close games, offense in the first quarter, and variance (see VARIANCE). A description of the original methodology is here, although the variables involved have since been tweaked.
4QC: Fourth-quarter comeback. At the team level, this is any game where a team wins after trailing in the fourth quarter (or in modified overtime). At the quarterback/offense level, Scott Kacsmar introduced this stat at Pro-Football-Reference in 2009, correcting the myth that John Elway had the all-time record with 47 4QC. Elway actually had 34 4QC wins, the same amount as Johnny Unitas, because Denver counted games where Elway never trailed in the fourth quarter. Dan Marino actually had the record with 36 4QC, which has since been surpassed by Peyton Manning. Kacsmar credits a 4QC to a quarterback when he meets the following requirements:
Fred Edelstein Lock of the Week: The best bet of the week's college football games as chosen by Seventh Day Adventure podcast host Russell Levine and his weekly guests. Named after the former ESPN "insider" who is currently serving time for fraud.
F-Plus (F/+) Football Outsiders official college football ratings, combining play-by-play and drive-based efficiency systems developed independently by Bill Connelly and Brian Fremeau. F/+ ratings represent the best measure of overall college team performance we've measured in terms of predictive quality and retrodictive analysis.
Fremeau Efficiency Index (FEI) College football rating system created by Brian Fremeau based on measuring the success rate of a college football team scoring and preventing opponent scores during the non-garbage possessions of a game. Like DVOA, FEI rewards playing well against good teams, win or lose, and punishes losing to poor teams more harshly than it rewards defeating poor teams. Unlike DVOA, it is drive-based, not play-by-play based, and it is specifically engineered to measure the college game.
FO Game Charting Project: Project initiated in 2005 where FO readers charted all NFL games in order to produce statistics that are publicly unavailable, including yards after catch, assigned defenders on pass plays, offensive formation on each play, and numerous other facts.
Guts: Any win by 1-8 points over a team that will finish the season with a record over .500. This term comes from an article written for FOXSports.com in 2005, and republished in Pro Football Prospectus 2006, demonstrating that big wins over bad teams are a better indicator of future success than close wins over good teams. The four terms introduced in this article:
GWD: Game-winning drive. Arguably the first known usage of drive stats, the game-winning drive is the offensive scoring drive that puts the winning team ahead for the last time in the fourth quarter or overtime. Very similar to fourth-quarter comebacks (4QC); the main difference is a GWD can happen in a game that is only tied. There does not have to be a deficit like in a comeback. Not all 4QC are GWD, not all GWD are 4QC, but they are definitely related statistics standardized by Scott Kacsmar for Pro-Football-Reference in 2009. A GWD opportunity is any game where the offense has possession of the ball in the fourth quarter or overtime with the score tied or trailing by one score. A 1-play, 0-yard drive that is just a field goal attempt does not count as a GWD.
Keep Choppin' Wood: Weekly award given by our column Scramble for the Ball to the player or coach who is most detrimental to his team through his poor play. Named for the Jacksonville Jaguars motivational slogan that caused punter Chris Hanson to hack his leg with an axe, thus going out for the year.
KUBIAK Projection System: Complicated system of statistical regressions used to project individual player statistics for fantasy football. Not an acronym; it was named after Houston head coach Gary Kubiak because he was a long time 80's backup, just like Bill Pecota, who gave his name to the player projection system over at Baseball Prospectus.
Leverage Rate: Percentage of a college football team's plays that take place on Non-Passing Downs, defined as all first downs, second down with 1-7 yards to go, or third/fourth down with 1-4 yards to go.
Lewin Career Forecast: Introduced in Pro Football Prospectus 2006 by David Lewin, and updated by Aaron Schatz here, the LCF was our system for projecting the peak success of college quarterbacks entering the NFL. It was replaced by QBASE starting in 2015.
Loser League: A fantasy football league originated by Football Outsiders where we choose six players every week that we expect to play poorly, but still meet minimum requirements. The goal is to score the fewest points.
FO Message Board Curse: Term used to describe the tendency of NFL teams to lose games after their fans flood the FO message boards with angry complaints about a low appearance in the DVOA ratings. Examples in 2005 include the 3-0 Washington Redskins losing to Denver in Week 5, the 5-1 Broncos losing to the New York Giants in Week 7, and, most famously, the 6-2 Atlanta Falcons losing to the previously 1-7 Green Bay Packers in Week 10.
Open-Field Yards : Average yards per carry that come more than 10 yards past the line of scrimmage. Represents yardage on long runs not included in Adjusted Line Yards.
The Penalty: In discussions of the Loser League, this is the 15 points scored by a running back who does not carry the ball 10 times, a quarterback who does not pass 10 times, a wide receiver who does not catch two passes, or a kicker who does not play due to injury or general suckitude. A kicker who simply gets no opportunities because his team is shut out does not get the penalty.
Playmaker Score: Fully introduced in Football Outsiders Almanac 2009 by Vince Verhei, then redesigned by Nathan Forster in 2014, Playmaker Score is a system for projecting the peak success of college wide receivers entering the NFL. In its current form, the system applies to all wide receiver prospects, and is based on a weighted combination of five factors:
Plus/Minus (+/-): Introduced in Football Outsiders Almanac 2010 by Bill Barnwell, a metric that compares a receiver's actual number of catches to his "expected" number of catches after adjusting for uncatchable passes, the distance of the routes the receiver runs, the situations in which he's thrown the ball, and the catch rates of his teammates. The resulting figure is the number of actual catches above or below the expected catches, explaining the name. The Saints' Marques Colston led all receivers in 2011 with a team-adjusted plus-minus of 15.7 catches above expectation, while the Broncos' Eddie Royal had a league-worst -8.1 catches below expectation.
POWER (rushing stat): Percentage of runs on third or fourth down, two yards or less to go, that achieved a first down or touchdown. Also includes runs on first-and-goal or second-and-goal from the two-yard line or closer. Not adjusted for opponent. This is the only statistic among the Football Outsiders offensive and defensive line stats that includes quarterbacks as well as running backs.
Point to Recover: The theory that officials will give a fumble recovery to whichever team is pointing more strenuously. Honestly, when everyone piles on, this is probably just as accurate as any other method.
PPP: EqPts Per Play. See EqPts.
Pro Football Prospectus: Running from 2005 to 2008, original version of the annual book written by the staff of Football Outsiders. Included essays on every team, statistical tables, new research, and KUBIAK fantasy football projections plus advanced FO stats and player comments for "skill players." Replaced in 2009 by Football Outsiders Almanac.
Program FEI A multiple-year rating for a college football program that incorporates five years of the Fremeau Efficiency Index to get a more accurate forecast for the upcoming season. See FEI.
Pythagorean Theorem: The principle, made famous by baseball analyst Bill James, that states that the record of a baseball team can be approximated by taking the square of team runs scored and dividing it by the square of team runs scored plus the square of team runs allowed. Statistician Daryl Morey later extended this theorem to other sports including professional football. Teams that win a game or more over what the Pythagorean theorem would project tend to regress the following year; teams that lose a game or more under what the Pythagorean theorem would project tend to win more the following year, particularly if they were 8-8 or better despite underachieving.
QBASE: Fully introduced in 2015 by Andrew Healy, QBASE is a system for projecting the peak success of college quarterbacks entering the NFL. The system applies to all quarterbacks taken in the first 100 picks of the draft, and is based on three factors:
ROBO-PUNTER: A theoretical punter whose punts were high enough and far enough to be downed at the one-yard line every single time. Discussed ad absurdum in the discussion thread for this article. This nickname also seems to have been borrowed by Pittsburgh Steelers fans to refer to Daniel Sepulveda. We would like royalties. No, no, we're kidding.
S&P: Combination of two measures, Success Rate and PPP (EqPts Per Play). S&P combines measurement of efficiency with Success Rates and explosiveness with PPP, similar to the way baseball analysts use OPS to combine On-Base Percentage and Slugging Percentage.
SackSEER: Introduced in Football Outsiders Almanac 2010 by Nathan Forster, and updated in Football Outsiders Almanac 2012, a system for projecting the peak success of college edge rushers coming into the NFL. The original version projected first- and second-round picks based on a weighted combination of the player's vertical leap, short shuttle run time, adjusted per-game sack productivity in college (SRAM), and total games of collegiate eligibility missed for reasons other than early draft entry (maximum of 48). In it's current form, SackSEER v2.0 expands the system to all drafted edge rushers, and includes collegiate passes defensed per game as an additional factor.
Scramble for the Ball: A weekly Football Outsiders column which serves as our main forum for discussing both fantasy football and weekly betting lines. One of the two original columns from the founding of Football Outsiders in 2003 (the other being weekly DVOA commentary). Named after the game-opening gambit in Vince McMahon’s short-lived XFL where, instead of flipping a coin to determine possession, two players raced from the sideline and the first one to grab the ball at midfield gained the opening possession for his team. Authored by Al Bogdan and Ian Demsbky (2003); Al Bogdan and Vivek Ramgopal (2004-2005); Bill Barnwell and Ian Dembsky (2006); Bill Barnwell solo (2007); Ben Riley and Vince Verhei (2008); Mike Kurtz and Tom Gower (2009 to present).
Second-Level Yards : Average yards per carry that come 5-10 yards past the line of scrimmage. Represents yardage that only gets half-credit when computing Adjusted Line Yards.
Similarity Scores: Method for comparing conventional stats of two different players, for just one season or over a two-year or three-year career span. Described in full here.
Situation-Neutral Pace: Seconds of game clock used per offensive play, with the following restrictions: drives are not included if they begin in the fourth quarter or final five minutes of the first half, and drives are only included when the score is within six points or less. A lower number indicates a faster pace. Pace stats are given in Football Outsiders Almanac (and occasionally on our website) for both offense and defense, but defensive pace is a representation of how a defense is approached by opponents, not an indicator of the strategy of the defense itself.
Skates, Stomps: See Guts.
Speed Score: Fully introduced in Pro Football Prospectus 2008 by Bill Barnwell, a system for projecting the success of college running backs entering the NFL. Combines a player's weight with his 40-yard dash time from the NFL scouting combine, thus accounting for the fact that a larger back is more likely to be a good NFL player than a small back with the same speed. Speed Scores generally range from 80 to 120, with 100 as the average. Formula is (weight*200) / (40-time^4).
Stops: The total number of plays by a defensive player that prevent a successful play by the offense, defined as 45% of needed yards on first down, 60% of needed yards on second down, and 100% of needed yards on third or fourth down. In general, "plays" refers to tackles, passes defensed, fumbles forced, or interceptions. The exception is when discussing pass defense data from the FO game charting project, in which case "plays" refers to all charted passes with the given player as the listed defender.
Success Points: Value of a play determined by both the total yards gained and the yards gained as a percentage of distance needed for a first down. Success points compared to league average for that situation become VOA. More here.
Success Rate: There are three stats called Success Rate.
The Tennessee Run Defense Problem: The conundrum where yards/play and DVOA may not fully indicate the quality of a defense because this defensive unit scares other teams away from rushing or passing. Therefore, when teams do in fact rush or pass against the defense, the defense may be unprepared and perform at a level that seems average. Because of this, it is difficult to tell if the defensive unit is actually as good as its reputation, or if the reputation scares other teams away from challenging an overrated defensive unit.
VARIANCE: A measure of a team's game-to-game consistency as judged by total DVOA rating for each game. A lower number represents more consistency (in 2011, Atlanta and Cleveland) and a higher number represents less consistency (in 2011, Buffalo and Baltimore).
VOA: Value Over Average. This is DVOA, with three main differences: it is not adjusted for opponent, it is not adjusted to make all fumbles equal (lost or recovered), and special teams are not adjusted for weather and altitude.
Weighted DVOA: A version of DVOA that gives recent games more weight than games early in the season to try to get an idea of how teams have improved or declined over time. Discussed here.
YAR: Yards Above Replacement. This is DYAR without opponent adjustments.