In most North American sports, the phrase games behind or games back (often abbreviated GB) is a common way to reflect the gap between a leading team and another team in a sports league, conference, or division.
Example
In the below standings from the 1994 Major League Baseball season, the Atlanta Braves are six games behind the Montreal Expos. Atlanta would have to win six games, and Montreal would have to lose six games, to tie for first. The leading team is by definition zero games behind itself, and this is indicated in standings by a dash, not a zero.
Computing games behind
Games behind is calculated by using either of the following formulas, in which Team A is a leading team, and Team B is a trailing team. Example math in this section uses the above standings, with Montreal as Team A and Atlanta as Team B.
Alternately:
Notes: It can alternately be said that Montreal is six games ahead of Atlanta. A games behind situation can change rapidly when two teams contesting for the lead play each other. For example, Atlanta could cut Montreal's lead in half (to three games) by sweeping a three-game head-to-head series. The leading team, in terms of games behind, is the team with the best won–loss difference. This is not always the team with the most wins. For example, a team with an 80–70 record (10 more wins than losses) would be one game behind a team with a 79–67 record (12 more wins than losses).
Anomalies
A games behind calculation can be misleading when attempting to compare teams that have played an unequal number of games. This is because the games behind calculation simply computes the difference between wins and losses for each team, and then averages those two numbers. Essentially, this treats each unplayed game as being a tie (i.e. win and a loss).
In an extreme example, attempting to compare the records of the 2007 New England Patriots (16–0; 1.000 winning percentage) and the 1972 Detroit Tigers (86–70; .551 winning percentage) finds that the teams are equivalent on a games behind calculation, as each team won 16 more games than it lost. However, the Tigers played 140 more games than the Patriots. The Patriots' 140 "unplayed" games are essentially treated as 70–70; indeed, if the 16–0 Patriots had 70 more wins and 70 more losses, their 86–70 record would match that of the Tigers.
In reality, teams in an actual sports league can have an unequal number of games played due to various scheduling anomalies, postponements, or cancellations. This can result in:
Two teams with different winning percentages may be tied in terms of games behind. For example, Team A at 6–4 would be tied with Team B at 4–2, in terms of games behind; however, Team B has the better winning percentage, at .667 compared to .600 for Team A. A team with a lower winning percentage may lead (in terms of games behind) a team with a higher winning percentage. For example, Team A at 6–4 would lead Team B at 2–1 by a half-game when calculating games behind. However, Team B has the better winning percentage at .667, compared to .600 for Team A.
Such conditions have occurred multiple times in major sports leagues, examples include:
Leagues generally use winning percentage to order teams in official standings. However, standings appearing in newspapers or online may order teams based on games behind.
Usage
The games behind calculation is often used in professional baseball and basketball, where tie games are not permitted. Standings for these sports appearing in print or online during a season usually will have teams ordered by winning percentages, with a "GB" column provided as a convenience to the reader. Games behind is used less often in American football, where ties are possible but relatively uncommon. Games behind is rarely used in ice hockey and soccer, where ties are or were traditionally common and standings points are typically used.
Major League Baseball
Major League Baseball (MLB) defines games behind as "the average of the differences between the leading team wins and the trailing team wins, and the leading teams losses and the trailing team losses." A games behind column almost always appears in MLB standings for each five-team division.
Wild card race
In the 1994 MLB season, the American League and National League each split into three divisions, and each added a wild card team to the playoffs. Following this change, it became common for the media to publish an additional set of standings for the wild card race. It included all teams from a league, with the exception of the division leaders, and games behind was calculated with respect to the team with the highest standing in the wild card race.