The 2015 Pittsburgh Pirates season was the franchise's 134th season overall, the 129th season as a member of National League, and 15th season at PNC Park.

The 2015 New York Mets season was the 54th season in the franchises' history. The Mets finished the regular season with a record of 90–72, winning the National League East title on September 26, their first division title since 2006 and sixth overall. They defeated the Los Angeles Dodgers in the NLDS in five games and swept the Chicago Cubs in the NLCS. They lost to the Kansas City Royals in five games in the 2015 World Series. It was the Mets' first appearance in the World Series since 2000 when they lost to the New York Yankees. It marked the team's first winning season since Citi Field opened in 2009.