Major League Baseball tie-breaking procedures

One-game tiebreakers are played between teams tied for a division championship or a league's second wild-card berth. These games are to be played the day after the season is scheduled to end. Home-field advantage is determined using the rules listed below ("Breaking Ties Without Playoff Games").

From the implementation of the wild-card in 1994 to the end of the 2011 season, a different rule was in place. Two teams tied for a division did not play a tiebreaker if their records were better than all non-division winners in their league. Instead, said tie was broken using the rules listed below ("Breaking Ties Without Playoff Games"). This scenario happened in the 2001 Major League Baseball season when the Houston Astros and St. Louis Cardinals tied for first place in the National League Central. The Astros were awarded the division title by virtue of a better head-to-head record against the Cardinals, while St. Louis received the wildcard berth.

With, however, the adoption of a second wild-card berth and a Wild Card Game beginning in the 2012 season, the non-division winner with the best record in the league faces possible elimination on the first day of the postseason. As a result, the tie-breaking rules were changed so that two teams tied for a division championship must play a tiebreaking game even if both teams have already qualified for the postseason. The team losing the tie-breaking game will now qualify for a wild-card berth only if its regular-season record is among the league's two best records for non-division-winners. If that team is tied for the second wild-card spot, a second tie-breaking game would then be played.

If, on the other hand, two teams are tied for the first wild-card spot, no tie-breaking game is played. Rather, the two teams simply play against each other in the Wild Card game, with home-field advantage awarded using tie-breaking rules described in the next section.

1. The team with the better head-to-head winning percentage during the regular season.
2. The team with the best overall record in intradivision games.*
3. The team with the best overall record in intraleague games.
4. The team with the best record in the final 81 games of the season, ignoring interleague play.
5. The team with the best record in the final 82 games of the season (provided the game added is not between the tied teams), continue one game back until the tie is broken (Interleague games are skipped and ignored in this process.)

*all current references in mlb.com website indicate that this rule applies even for teams that are not in the same division.

If two champions from separate divisions have the same record, the tiebreaking procedure listed above is used to determine postseason seeding. No additional games are played.

Tied teams are designated as A, B, C, and D. Choice for one of these designations is first given to the team winning the tie-breakers (listed below). While A is usually the "best" designation, there are some scenarios where C has a different path to the postseason. If a division title is up for grabs, then those divisional teams will select from the first designations (A, B,...).

On Day 1, A will host B and C will host D (if there is no fourth team, C will be considered to have won this game). Games on Day 2 may occur as follows:

1. If the teams are all competing for 1 playoff spot, then the A/B winner will host the C/D winner for that spot.
2. If 3 teams, not all tied for the same division lead, are competing for 2 playoff spots, C will host the A/B loser for the second spot.
3. If 4 teams were competing for 3 playoff spots, and two teams are competing for the division championship, then the A/B loser will play the C/D loser for the final wild-card spot. Home field will be determined by the rules for two way tiebreakers.
4. If 4 teams were competing for 3 playoff spots, and three teams are competing for the division championship, if D wins, then the A/B winner wins the division and Club D is a wild card, with the A/B loser then hosting C for the other wild card.[1] If D loses, then the A/B winner hosts team C for the division, and the loser is a wild card, and the A/B loser hosts team D for the other wild card.
5. If 3 or 4 teams, tied for the same division's lead, both win on Day 1, then the A/B winner will host the C/D winner to determine the division title. The loser of this Day 2 game will earn a wild card spot. If four teams are competing for three spots, the A/B loser hosts the C/D loser for the a wild card.

The order in which teams pick their designations (A, B, C, D) will be determined by the following 5-step tie-breaking system. If there is a tie for both wild card and division title spots, then the first designations will match teams competing for their division title.

1. Winning/Losing season series against each of the other tied teams (only if a 3 way tie)
2. Winning percentage among all tied teams
3. Winning percentage in intradivision games
4. Winning percentage in the last half of intraleague play
5. If still tied, the next most recent intraleague game is added into this winning percentage (skipping games between tied teams) until not all teams are tied.

If at any given step some, but not all, teams remain tied, then those teams that are still tied revert to Step 1.