How Would Realignment Affect Playoff Races?

Over the weekend Buster Olney reported that Major League Baseball and the players’ union discussed a possible plan for realignment. The plan would move the Houston Astros, or possibly the Florida Marlins, to the AL so that both leagues would have 15 teams; eliminate the three divisions within each league; have the top-five teams from each league go to the playoffs; and require an inter-league game every day (because of the odd number of teams in each league). There is lots to consider with such a realignment — fairness, logistics, etc. — but I wanted to look at a single aspect: how will this plan would affect the number of competitive playoff races at the end of the season?

With the top-five teams in each league making the playoffs, instead of three division leaders and a wild card, the playoff picture would change. Would this mean more or fewer competitive races at the end of the regular season? To quantify this I counted the number of playoff teams that wouldn’t have made the playoff if they had won three fewer games, and then counted the number of non-playoff teams that would have made the playoffs if they had won three more games. Though not perfect, I think this is a good proxy for the “end-of-season” excitement. I counted this number under the current alignment and under the realigned leagues.

Here, as an example, is the AL from last year. Teams in italics made the playoffs and bolded teams met my “competitve-race” criterion.

AL East		AL Central		AL West
Tampa Bay Rays	96	Minnesota Twins	94	Texas Rangers	90
New York Yankees	95	Chicago White Sox	88	Oakland Athletics	81
Boston Red Sox	89	Detroit Tigers	81	Los Angeles Angels	80
Toronto Blue Jays	85	Cleveland Indians	69	Seattle Mariners	61
Baltimore Orioles	66	Kansas City Royals	67

In this case I get zero competitive teams. If either the Rays or Yankees won three fewer games they still would have made the playoffs since the Wild Card saves them. Here are the same wins under the realigned system, with the Astros included.

Tampa Bay Rays	96
New York Yankees	95
Minnesota Twins	94
Texas Rangers	90
Boston Red Sox	89
Chicago White Sox	88
Toronto Blue Jays	85
Oakland Athletics	81
Detroit Tigers	81
Los Angeles Angels	80
Houston Astros	76
Cleveland Indians	69
Baltimore Orioles	66
Kansas City Royals	67
Seattle Mariners	61

Under the new system the same four teams would have made the playoffs, but they would have been joined by the Red Sox. Here, though, there are now three teams that meet my competitive-race criterion. Three fewer wins for the Rangers or Red Sox pushes them out of the playoffs and three more from the White Sox puts them in.

Doing the same for all the years back to 1995:

Year	AL Current	AL Realigned	NL Current	NL Realigned
1995	3	4	3	2
1996	4	5	3	0
1997	0	3	2	0
1998	2	4	3	0
1999	0	0	3	0
2000	5	2	0	3
2001	0	0	3	0
2002	0	3	2	0
2003	3	2	2	6
2004	3	5	4	3
2005	2	3	3	5
2006	0	3	6	2
2007	0	2	7	2
2008	2	5	5	3
2009	2	5	0	3
2010	0	3	3	0
Average	1.63	3.06	3.25	2.13

Over the past 15 years this new system would have made the AL almost twice as competitive and the NL about a third less competitive. Overall an extra 0.3 teams would be in a competitive race per year. So the realignment would have slightly, but not drastically, increased the number of teams in the playoff hunt. Although it would change which teams were in the hunt, the new system would make it easier for teams from good division, e.g. the AL East, to make the playoffs.