Strength of schedule

In sports, strength of schedule (SOS) refers to the difficulty or ease of a team's/person's opponent as compared to other teams/persons. This is especially important if teams in a league do not play each other the same number of times.

Computation

The strength of schedule can be calculated in many ways. Prior to American football's Bowl Championship Series (BCS) removal for the 2004 season, [ [http://www.bcsfootball.org/bcsfb/history BCS Chronology] , BCSFootball.org.] the SOS was calculated as follows, where OR is the opponents' record, while OOR is the opponents' opponents record. [ [http://www.nationalchamps.net/NCAA/BCS/strength_of_schedule_explain.htm Strength of Schedule] NationalChamps.net]

Other calculations include adding the opponent's power ratings and multiplying them by the number of games, or a modification by assigning weights (higher weights for "stronger" teams). [ [http://www.laxpower.com/update07/ex_sos.php Strength of Schedule] , Laxpower.com]

Furthermore, several more factors maybe added, such as the position of the team in the league, the strength of the team's division or conference, which game counts in the formula and which doesn't (vital in the Bowl Championship Series), the location of the game (see home team and home advantage) and others.

Use

The BCS previously used the SOS in its formula to determine which teams will play in BCS Bowls, and more importantly, to the BCS National Championship Game. Furthermore, although several other leagues don't incorporate SOS directly into team standings, the standings are influenced by the teams participating in a division/conference since some divisions/conferences may have tougher teams, and these teams play each other more frequently as compared to other teams playing in other divisions/conferences.

For example, in the National Football League (NFL) the 32 teams don't face each other in a season, since there are only 16 games per season. The NFL is divided into 2 conferences, which is further divided into 4 divisions per conference. Each team plays a team from their division twice, teams from another division in the same conference once in a four-year cycle, teams from another division of the other conference once in a four-year cycle, and two other teams having the same places in the conference from the prior season. In other words, a weak team would play other weak teams, while a team will play the teams from their division no matter the strength. [ [http://football.about.com/cs/football101/a/bl_schedproced.htm Football 101 - NFL Scheduling Procedures] , About.com]

Major League Baseball (MLB) has a more extreme way of scheduling since interleague games are done rarely, and were only introduced in 1997, plus the fact that interleague games do not exactly have concrete rules, save for the number of rest days and doubleheaders. [ [http://mlb.mlb.com/news/article.jsp?ymd=20060404&content_id=1383448&vkey=news_mlb&fext=.jsp&c_id=mlb The schedule is a Major undertaking] , Major League Baseball official website.]

In the National Basketball Association (NBA), the 30 teams are all guaranteed to face each other at least twice in an 82-game regular season, although intra-division games are more frequent (as much as four times) than intra-conference games (twice). In the National Hockey League, some teams may not even meet each other, and intra-division games are more frequent (eight times) when compared to the NBA. A strong team in a weak division or conference is capable of bloating their record in order to have a better seeding in the playoffs.

In order to resolve differing strengths of schedule among teams, the playoffs is held after the season to determine which team will win the championship. The best teams from each conference qualify and are done at a variety of formats. The playoffs conclude with a championship game or series with the two teams representing their own conferences. The playoffs may also award a home advantage to a team with a superior record, regardless of their SOS, although the NFL holds its championship game at a predetermined site, while the MLB awards the home-diamond advantage in the World Series to the team representing the league that won the All-Star Game.

The concept of "strength of schedule" is alien to European domestic leagues since each league is not divided into divisions or conferences (the meaning of "conference" is different here, since even though several leagues maybe in one conference, teams from the same conference do not play teams from other leagues of the same conference. See Football Conference for an example.), and every team plays every opponent twice (home and away) and as such, no playoffs are usually done to determine the winner; the team with the best record wins the championship outright, with several tiebreaking criteria to determine a team's overall standing.

One exception is the Scottish Premier League where after 33 games, the division is split into two halves; the teams then play teams from their half once to determine the champion. This will lead a seventh-place team (there are 12 teams) prior to the split having a better record than the sixth-place team since they'll play relatively easier games as compared to the sixth place team (although it maybe mathematically impossible for them to win the championship).

In inter-European competition, no permanent divisions or groups are instituted although qualifying teams are drawn into different groups, where the top teams per group advance into the "knockout stage" which is almost similar to concept of "playoffs" in North American sports.

References