Forty-three years after Major League Baseball‘s postseason expanded from two to four teams with the advent of divisional play and 17 years after the it doubled from four to eight with the addition of a wild card in each league, the playoffs will go to 10 when a pair of one-game wild card elimination games open the 2012 postseason on Friday, October 5.

The wild card games, pitting the two best non-division winners in each league, are scheduled to take place two days after the end of the regular season. Through Tuesday, August 14, the Baltimore Orioles and Tampa Bay Rays (each 63-53) led the AL wild card race while the Atlanta Braves (67-49) and Pittsburgh Pirates (64-52) led the NL wild card derby.

If there is a tie for one or both wild card spots, playoff games to determine the wild card teams will be played Thursday, October 4. Through Tuesday, August 14, there were five American League teams within 3 ½ games of the wild card spots and five teams within six games of the wild card spots in the National League.

The winner of each wild card game will advance to the best-of-five Division Series and will host the first two games against the division champion with the best record in its league. The Division Series are scheduled to begin Saturday, October 6 in which division champions play each other. The Division Series between the wild card winner and the top overall seed in each league will start Sunday, October 7.

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The American League Championship Series is scheduled to begin Saturday, October 13 and the National League Championship Series is scheduled to start Sunday, October 14. The World Series, which will open at the National League champion because the NL won the All-Star Game in July, is scheduled to begin Wednesday, October 24.

If the World Series goes seven games, the finale will be played Thursday. November 1, which would mark the third time in the last four years the World Series has extended into November. The start of the MLB regular season schedule has been pushed up each of the last two years so that the playoffs don’t last beyond October, but that implementation took place before the second wild card team was added.

The additional wild card teams and games haven’t won the approval of many traditionalists, even those who could most directly benefit from more teams reaching the playoffs.

“You shouldn’t get nothing for second or third,” Philadelphia Phillies manager Charlie Manuel told reporters, via The Sporting News, during spring training. While the Phillies are all but out of the playoff race this year, they won the NL East each of the previous five seasons and would have reached the one-game playoff in both 2005 and 2006.

“I’m not knocking baseball at all, but in my opinion, I’d like to see the two…best teams in the World Series,” Manuel said.

The MLB postseason consisted only of the American and National League champions advancing to the World Series until 1969, when expansion to Kansas City, Seattle, Montreal and San Diego increased the number of teams to 24 and resulted in the formation of four divisions.

MLB added a division and a wild card team in each league in 1994, but the players’ strike brought the season to a halt on August 12 and forced the cancellation of the playoffs and World Series, which meant the first wild card teams reached the postseason in 1995.

Still, even with the addition of a second wild card team, Major League Baseball has the smallest percentage of teams reaching the playoffs of the four major American professional sports. The NBA and NHL each have 16 of 30 teams qualify for the playoffs while 12 of the 32 NFL teams (38 percent) reach the postseason.