Football Glossary and Football Statistics Glossary
Is there something at the site that needs more clarification and should be listed here? Please let us know about it.
1st team all-pro
- On the player and team pages, the words "all-pro" now mean first-team all-pro, according to the Associated Press all-pro team from
1940--present or the UPI team from 1931--1939.
- two-point conversions made.
- attempts (either passing or rushing) per game.
- adjusted net yards per passing attempt: (pass yards + 20*(pass TD) - 45*(interceptions thrown) - sack yards)/(passing attempts + sacks). See AY/A
Note that we are now using 20 yards per TD instead of 10, because of research by Chase Stuart at the
- the number of times the player was named first team all-pro
- assists on tackles. See tackles
. Pre-1994, assists are grouped with tackles. From 1994 to 2000, assists were unofficial but consistently
recorded and should be complete in our database. From 2001 to the present, they are an official statistic.
- attempts. If in a rushing table, this is rushing attempts. If in a passing table, it means passing attempts.
- approximate value. This is our attempt to put a single number on each player-season since 1950 so that we can (very approximately) compare across years and across
positions. See this blog page
for all the details.
- on coach's pages, this number is the average finish, within the division, of that coach's teams.
- adjusted yards per passing attempt: (pass yards + 20*(pass TD) - 45*(interceptions thrown))/(passing attempts). This stat was introduced, and the reasoning
behind it thoroughly explained in a book called The Hidden Game of Football
, by Bob Carroll, Pete Palmer, and John Thorn.
Note that we are now using 20 yards per TD instead of 10, because of research by Chase Stuart at the
- blocking back (in the single wing).
- punts had blocked.
- career approximate value. See the entry on AV
. The Career AV is computed by summing 100% of the player's best-season AV
95% of his second-best-season AV, 90% of his
third best, and so on. The idea is that the Career AV rating should weight peak seasons slightly more than "compiler"-type seasons.
- completion percentage: completions/(passing attempts).
- this is an estimate of what the team's record "should have been," given the team's points scored and allowed. The concept goes back to baseball analyst
Bill James' Pythagorean formula
. We wrote a little about it in this
- fantasy position. This is (for now) always either QB, RB, WR, or TE. The reason we need this column is that, to compute VBD
player needs to be classified as one and only position. It gets a bit problematic for players like Eric Metcalf who played different positions at different points in their career. If you see a
player-season that is misclassified, please let us know
- fantasy points: (passing yards)/20 + (rushing yards + receiving yards)/10 + 6*(passing TDs + rushing TDs + receiving TDs) - 2*interceptions
- forced fumbles. We are still working on integrating this into our data set.
- field goals attempted.
- field goals made.
- fumbles. This includes all fumbles, including those that were recovered by the fumbler's team.
- fumble recoveries.
- games played.
- games started. This is complete from 1980 forward, and partially complete before that.
- in a passing table, this means intercpetions thrown. In a defensive table, it means interceptions caught.
- left halfback.
- long gain. This was the player's (or team's) longest gain of the season in that particular category.
- left safety.
- middle guard (in a 5-2 defense).
- net yards per passing attempt: (pass yards - sack yards)/(passing attempts + sacks).
- other TDs: all touchdowns that were not rushing, receiving, kickoff return, punt return, interception return, or fumble return touchdowns.
- overall rank (for fantasy football). This denotes the player's overall rank (among all players, not just those at his position) for that season. See also
and fantasy points
- the number of times the player was a pro bowler
- passes defensed. A relatively new stat. We are still working on integrating it into our data set.
- position. Note that this is upper-case if the player was his team's primary starter at the given position, it is lower-case if the player started some games but
was not his team's primary starter. It is blank if the player did not start very many games (or none at all). There are no hard-and-fast rules for exactly who gets classified as a primary
starter, a part-time starter, or a non-starter, but the information has been provided to us by the editors of the ESPN Pro Football Encyclopedia, who have made these designations after much
- position rank (for fantasy football). This denotes the player's rank within his position for that season.
See also VBD
, fantasy points
, and OvRank
- A player is considered a pro bowler if he was named to the pro bowl as a starter, a reserve, or an injury replacement. If named to the team, a player
is considered a pro bowler even if he does not attend the pro bowl due to injury.
- receptions per game.
- passer rating. Note that pro and college football use different formulas. Some details can be found
- right halfback.
- rushing TDs plus receiving TDs.
- right safety.
- split end.
- in a passing table (1969--present), this refers to times sacked. In a defensive table, it refers to the number of sacks a player or team made. For individuals,
sacks have only been an official stat since 1982.
- sack percentage: (times sacked)/(passing attempts + times sacked).
- the number of seasons in which the player was his team's primary starter at his position.
- in the team stats section of a coach's page, this denotes the team's takeaway/giveaway rank.
- tailback (in the single wing).
- passing TD percentage: (passing TD)/(passing attempts).
- tackles. We have tackle data for all players who were active in 1994 or later. Prior to 1994, the tackle data is unofficial, inconsistently recorded from team to
team, and incomplete in our database. Also, before 1994, some teams recorded assists while others didn't, so we have lumped tackles plus assists together in the tackles column for those
years. From 1994 to 2000, tackles were not an official stat, but were recorded consistently and should be complete in our database. From 2001 to the present, tackles have been an official
- the player's fantasy value for the season. VBD stands for Value-Based Drafting, but the initials have come to stand for the result of the method (i.e. the value
of the player) in addition to the method itself. The method was popularized by Joe Bryant of footballguys.com
in the early 90s.
Essentially, the idea is this: the value of a player is the difference between his fantasy points
and a baseline, with the baseline being defined as the number of fantasy points that a relatively cheap replacement would get.
I've defined the baselines as the fantasy point totals of the #12 QB, the #24 RB, the #30 WR, and the #12 TE for each season.
I won't go into detail on why I chose these numbers, but if you are a fantasy footballer, you probably
have some idea.
Anyway, here's an example. In 1975, O.J. Simpson had 362 fantasy points. The #24 ranked running back that year
was John Brockington who had 116 fantasy points. Thus, O.J.'s value for 1975 is defined to be 362 - 116, which
is 246. But wait, there's just one more thing. Since the NFL schedule was only 14 games long back in those
days, I'll multiply that 246 by 16/14 to get 281 (I've also adjusted the values for the strike-shortened seasons of 1982 and
1987 in this way).
NOTE: any player who is below the baseline will be counted as having zero value.
- wingback (in the single wing).
- extra points attempted.
- extra points made.
- yards per attempt.
- yards per completion.
- yards per game.
- yards per reception.
- yards from scrimmage. That is, rushing yards plus receiving yards.
Explanation of the Advanced Passing table
This is a quick look at how a quarterback did compared to league average in eight different passing stats:
yards per attempt
adjusted yards per attempt
net yards per attempt
adjusted net yards per attempt
passing TD percentage
First, for each stat for each year for each league, we computed two things:
- the league average for that stat in that league
during the three-year period with the given year in the middle. For example, the "league average" for the 1963 AFL would
be the aggregate average of the stats accumulated in the AFL from 1962 to 1964. (NOTE: the 1960 AFL and the 1969 AFL, as well
as the current season, will be based on only two years worth of data rather than three.)
- the standard deviation of the stat for all individuals who had 14 or more pass attempts per scheduled game during the
Next, we computed how many standard deviations away from the league average each player was in each of his seasons.
We multiply that number by 15 and add it to 100, and that is the number you see.
- On all stats, 100 is league average.
- On all stats (including sack percentage and interception percentage), a higher number means better than average
- The greatest passing seasons of all time are in the 140s. A typical league-leading season in most categories will be in the high 120s or the low-to-mid 130s.
Explanation of the similarity scores
At baseball-reference.com you'll find, for each player in baseball history, a list of players similar to that player.
These lists are generated by a method introduced by Bill James in the 1980s, and his aim was to find players who were
similar in quality, but also similar in style of play
The similar players lists here at pro-football-reference are NOT the same thing.
Unfortunately, football stats just aren't descriptive enough to capture players' styles. So we have settled for a method that
attempts to find players whose careers were similar in terms of quality and shape. By shape, we mean things like: how many
years did he play? how good were his best years, compared to his worst years? did he have a few great years and then several
mediocre years, or did he have many good-but-not-great years?
Essentially, if you run across a player you've never heard of before, and if the list of similar players has some names you recognize,
this gives you a quick way to (very roughly) figure out where the guy fits in history.
You can read more about it in this blog post