Hitting Momentum: Myth or Reality

Something you’ll hear a lot from announcers on tv and on the radio, is “If you’re on a hot streak heading into the playoffs your chances are better to win a World Series...” Or something like that.

What I’m looking at is the past 8 seasons of baseball, and using wRC+ to prove or disprove this theory. For each of those seasons, I’m looking at data from FanGraphs.com and MLB.com/stats for the month of September.

First let me give you a quick refresher on what these stats mean, if you don’t already know. According to MLB:

Same goes for team wRC+ stats. They show how well the teams create runs which is very useful in tight games in the playoffs.

2017

At the end of last season, the Yankees rode their playoff-team-leading 119 wRC+ to the ALCS. The eventual AL and World Series Champions, the Houston Astros, were 3rd among playoff teams at 113 wRC+. The Cleveland Indians finished right behind the Yanks at 112 wRC+ before falling to them in the ALDS. The Minnesota Twins were 4th at 110 wRC+, and the Boston Red Sox were 10th at an abysmal 78 which was also good enough for 29th in all of baseball. The Arizona Diamondbacks (101) and Chicago Cubs (97) were at 6th and 7th, while the Washington Nationals and Colorado Rockies finished way down the list and were both easily dispatched in the playoffs.

2016

In 2016 the Cubs beat the Indians in the World Series. The New York Mets would finish 1st at 108 wRC+ but were dropped by the San Francisco Giants who were 10th at 84 wRC+ (27th in MLB). The Cubs came in 3rd at 99 wRC+ and their opponent in the series Cleveland were 6th at 93 wRC+. The Texas Rangers were 4th at 98 wRC+. The NL runner-up Los Angeles Dodgers came in at 5th with 96 wRC+.

2015

2015 saw the Royals win their first title since 1985. The Astros led all playoff teams with 134 wRC+ in September, but were bounced in the ALDS by the Royals. 2nd on the list, the Toronto Blue Jays, had 128 wRC+ but only got to the ALCS. The NL Champion Mets were 4th at 115 wRC+. In fact, the only two playoff teams with a lower wRC+ than the Royals (104) in September of 2015 were the Pittsburgh Pirates (100) and St. Louis Cardinals (97), both victims of the Cubs.

2014

In 2014, things went a little haywire. The Dodgers (137) , Detroit Tigers (119), and Pirates (118) went 1-2-3 in wRC+ in September, and were all eliminated in the first round they played. The Angels and Orioles were 4th (106) and 6th (103), the Nationals also finished 6th, meanwhile the Cardinals were in 9th in wCR+ (88) behind the World Series teams San Francisco (97) and Kansas City (91) at 7 and 8. The Athletics were (79) 10th out of 10 and were 25th in the league overall. Yikes.

2013

The 2013 Red Sox were 2nd in wRC+ at 131 behind the Oakland Athletics on their way to the World Series title. Oakland, 1st at 133 wRC+, lost in the ALDS to Detroit, who was 9th out of the 10 playoff teams. The Atlanta Braves were 10th with only 90 wRC+ and it showed as they were bounced easily in the NLDS by Los Angeles, who had 101 wRC+. The Cardinals had a nice September with 104 wRC+ to be 4th en route to the NL pennant.

2012

The Giants were 3rd in wRC+ at 116 in September of 2012 on their way to the World Series. Their opponent, the Tigers finished 6th at 97 wRC+. On the opposite end, the Nationals were 1st with 119 wRC+ but lost to the Cardinals in the NLDS. The Yankees, 3rd at 116 as well, got to the ALCS. The Cardinals were 6th at 100 wRC+ on their way to the NLCS. The Braves, were 10th at 73 wRC+ and were bounced by the Cardinals in the NL Wildcard. 73 was also good enough to make Atlanta 28th out of the 30 MLB teams that September.

2011

2011 was the last year before the Wildcard play-in games in each league. The AL Champion Rangers led all playoff teams with a massive 144 wRC+. AL runner-up Detroit was right behind Texas at 142 wRC+. World Series Champion St. Louis finished 3rd at 122 wRC+. The Milwaukee Brewers, in their only appearance in this research, came in 4th at 117 wRC+. The Tampa Bay Rays were 5th at 111 wRC+, Arizona 6th at 104 wRC+, the Yankees 7th at 94 wRC+, and the Philadelphia Phillies came in way behind everyone else at 84 wRC+.

2010

The 2010 Phillies led the way that September with 120 wRC+ on their way to the NLCS. The Cincinnati Reds were 2nd with 103 wRC+ but fell to Philly in the NLDS. Tampa Bay (102) fell to the Rangers in th ALDS. Texas finished 5th at 97 wRC+ on their way to the AL pennant over the Rays. The Yankees were the other AL playoff team, coming in at 4th with 101 wRC+. The World Series Champion Giants were 6th at 91 wRC+. the other two playoff teams, Atlanta and Minnesota were 7th and 8th at 87 and 85 wRC+ respectively.

Conclusion

So, after all that, there’s definitely a correlation between creating a lot of runs in September, and then carrying that into October.

There are some exceptions to this rule though.

The Royals won the World Series in 2015 with an 8th-best wRC+. The 2014 Giants and Royals were 7th and 8th in wRC+ were another exception.

However, there isn’t quite enough evidence to say it’s a myth. The teams near the top of the league in wRC+ typically advance at least one round or more in the playoffs. The Nationals in 2012 and the entire top-3 in 2014 wewre eliminated early on.

I wouldn’t go as far as to say it’s a solid fact, but the evidence definitely leans towards it being more beneficial to be a hot hitting team heading into the postseason.

In case you were wondering, as of Tuesday night, of the potential playoff teams, the Dodgers are leading the way at 127 wRC+, the Athletics are right behind them at 122 wRC+, Houston at 115 wRC+, the surging Milwaukee at 104 wRC+, Cleveland at 103 wRC+, Atlanta and the Yankees both at 97 wRC+, the Cardinals at 95 wRC+, and Boston at 94 wRC+. Colorado is coming in at 90 wRC+ while the struggling Cubs are at 76 wRC+.

Take all of that however you’d like.