It is a logical assumption that it’s tougher to hit in the post-season than in the regular season, with back-of-the-rotation starting pitchers disappearing from view and the workloads of the very best pitchers being rationed less carefully. No longer are the top arms being saved for more important occasions — those post-season games are the most important occasions. The numbers back up the logical assumption, as you can see after the jump.
From 1903 through 1968, the post-season meant simply the World Series. Over the 65 seasons through 1968 that culminated in a World Series, the average major league regular season produced an overall OPS of .702, while the average World Series produced an OPS, in total for all plate appearances in the Series, of .641. The on-base and slugging components of OPS were each similarly affected: the averages for a regular season over this period were .329 OBP/.372 SLG, while the average World Series through 1968 produced a .300 OBP/.342 SLG
From 1969 through 2011 (not including 1994, which did not include a post-season), the average regular season produced a major league OPS of .726 (comprised of a .328 OBP and a .398 SLG), while the average post-season produced an OPS of .701 (comprised of a .317 OBP and a .384 SLG).
Over the 65 World Series years from 1903 through 1968, there were only ten seasons in which the OPS produced during the World Series was higher than the OPS produced by the majors as a whole during the regular season that led up to it. The biggest jump in OPS from the regular season to the World Series occurred in 1953, the year the Yankees completed their fifth world championship in a row and Billy Martin for once hit as hard as he partied (12 for 24 with two homers and two triples in the Series). The Yanks and Dodgers combined in that World Series for an .844 OPS, compared to a .733 OPS produced by the majors as a whole during the 1953 regular season. 1930 and 1950 saw the biggest drops in OPS from the regular season to the World Series during the pre-1969 era. The 1930 regular season generated the highest OPS and run scoring levels in modern baseball, exceeding even the biggest hitting seasons of the steroids era. The 1930 regular season OPS for the majors as a whole was .790 (higher even than the OPS in the year 2000). But in World Series that year, the Athletics’ fireballing combination of Lefty Grove and right-handed George Earnshaw dominated the Cardinals and the teams combined for an OPS of just .601, including a .546 OPS for the Cardinals, who had put up a team OPS in the regular season of .843 .
Over the 43 years from 1969 on that have produced a post-season, there have been only ten seasons in which the OPS produced during the post-season was higher than the OPS produced across the majors during the regular season that led to it. The largest drop over this period from regular season OPS to post-season OPS was 1983, when Baltimore’s pitching staff (the starters were Boddicker, Flanagan, McGregor and Storm Davis) held the White Sox and Phillies to only 11 runs scored over nine post-season games. That contributed to an overall post-season OPS in 1983 of just .614, compared to a major league-wide .714 OPS during the 1983 regular season.
On the flip side, the biggest jump in OPS from the regular season to the post-season in the division play era occurred in 1989, the year of the World Series earthquake that hit the territory that both competing teams, the Giants and A’s, called home. Among the noteworthy hitting displays that post-season: in the NLCS, the opposing first basemen, Will Clark and Mark Grace (please do not refer to them as Will and Grace) each posted batting averages over .600 with OPS numbers around 1.800. And after the earthquake stopped the Series for ten days between Game 2 and Game 3, the pitching staffs never really got back in sync, as Oakland won the last two games by the scores of 13 to 7 and 9 to 6 to complete their tragedy-haunted sweep. All told, the overall OPS for that post-season was .773, compared to a regular season OPS for the majors as a whole that year of .695. No, a jump like that in league-wide hitting from the regular season to the post-season is not quite as rare as a massive earthquake, but it certainly isn’t common.