KC Royals Late-Inning Rallies Not Improbable; They Were Built That Way


The KC Royals playoff run was one of the most improbable feats in sports history, if you buy into the Tweets, and many articles, flying around the internet citing the following set of facts:

Probability and statistics tells us the chance of two separate events both occurring is the multiple of each individual probability. In short, it would seem the odds of the KC Royals winning all of those games would be: .18 x .01 x .25 x .08 x .10 x .16 x .05 (for game 5, probability courtesy of Baseball-Reference). That calculation gives us the ridiculously unlikely 1 in 2.88 x 10^8  chance that a team wins all of those games.

That’s 1 in 34,722,222.

OK, the odds weren’t REALLY that remote because the KC Royals didn’t overcome all of those odds in consecutive games. The Kansas City Royals pulled off those seven wins over the space of 16 post-season games. Still crazy unlikely, but that fact reduces the improbability by quite a large margin.

Still, we’re looking at a blue moon event (and yes I’m not giving you a number because my memory of my college freshman course in probability and statistics isn’t clear enough for me to feel good about performing that calculation).

However, these odds come courtesy of Baseball-Reference’s win probability calculator which use box scores going back to the early 1900’s to predict outcomes using historical results in the same situation. These probabilities should be a pretty good estimate of current outcomes, UNLESS the team in question is designed to perform differently than their historical predecessors.

I humbly submit that the 2015 Kansas City Royals unique design was odd enough that those wins weren’t as unlikely as previous results would suggest.

For much of baseball history, relief arms were much less talented than starters. Today, relievers throw HARDER than starters. And the Kansas City Royals have owned a historic back end of the bullpen over the last two years.

No team in baseball history had three relievers prevent runs like Kelvin Herrera, Wade Davis, and Greg Holland did in 2014. In 2015, the KC Royals bullpen was on pace to be the most dominant late-inning force in MLB history until the entire team faded while enjoying a double-digit bulge over the Minnesota Twins in September.

Along with this “backwards” pitching staff, the Kansas City Royals added one of the best contact hitting lineups in baseball history. As this study from Grantland.com showed, contact-hitting teams seem to perform better against hard-throwing pitchers (which, in the last 10 years, describe most prime-time relievers).

Thus, is it really that surprising that the KC Royals would score more runs in the late-innings compared to their opponents? To me, that’s the Royals performing in accordance with their talent.

When you add in the subjective observation that the entire Kansas City Royals lineup seemed to get better at bats as the game progressed (likely because the team’s batters were very good at figuring out the opposing pitchers’ “plan” for each hitter), then you get results that seem much more improbable than they were.

Whatever the reason, those seven late-inning comebacks were a lot of fun to watch. No wonder they made KC Royals legend George Brett check his pulse.

Next: Alcides Escobar Finally Gets His Due

I was doing the same thing.