There Is No Special Higher-Stakes Home-Field Advantage

Here’s a post that probably doesn’t need to exist, but then, what post about baseball analysis does need to exist? If everything’s pointless, nothing is pointless, so let’s get to the subject! The Royals are shortly going to host the Giants for Game 6 of the World Series, and Kansas City is hoping to play again tomorrow, probably. If you imagine the whole baseball season as a baseball game, then we’re at the very end with an uncertain conclusion, meaning the leverage is enormous. If the purpose of every event is to help win a championship, well, now a championship hangs directly in the balance.

The Giants are up 3-2, but however much baseball remains will be played in Kauffman Stadium. And if you’ve been poking around today, you’ve probably seen some mentions of how that puts the Royals in a pretty decent position, all things considered. Not only do the Royals get to play at home — they get to play super-important games at home, with a super-frenzied atmosphere, and recent history might be on their side. I could cite any number of examples, but I will just cite this one:

And it’s the Jake they’d love to ride to a Game 6 victory, because a Game 7 would give the Royals a distinct home-field edge. (Giants fans can blame All-Star Game MVP Mike Trout for that possibility.) The home team has won each of the last nine World Series Game 7s. The last road team to win a Game 7 was the 1979 Pirates.

The Giants’ best bet, then, is to wrap this up in six.

What’s implied is that home-field advantage might get more significant as the stakes get higher and higher. Think of it as kind of a clutch home-field advantage factor. So can the Royals at least look forward to an extraordinary lift? No. I mean, no, probably.

This is covering ground that Mike Petriello covered a month ago. Back then, the playoffs hadn’t yet started. Now we’re almost finished, and we have a specific series in mind. So, I thought this called for a re-visiting. What does home-field advantage look like, exactly? During the regular season, the home team wins about 54% of the time. So that’s what that is.

What do we observe in the playoffs? Throughout baseball history, in the playoffs, the home team has won 54% of the time. Maybe you don’t have much use for what happened decades and decades ago, before people even knew about Albert Pujols. Let’s just go back 30 years, examining the window from 1985 to the present. The home team, in the playoffs, has won 55% of the time. Actually, 54.8%. And overall, throughout baseball history, it was 54.4%. No difference. Nothing here.

But, all right, we’re not in a position to be thinking about the playoffs overall — now we’ve got these high-leverage games. What those numbers above suggest is that there is no unusual high-leverage advantage, but we can do better. Historically, in World Series Game Sixes, the home team has won 64% of the time. Whoa, that’s something! And in World Series Game Sevens, the home team has won 50% of the time. That’s also something, in the other direction. That something basically negates the other something.

What about sudden-death games, in any round? Just because the World Series is the most important doesn’t mean it contains the only high-leverage playoff games. Historically, when both teams have had their backs against the wall, the home team has won 52% of the time. Examining just over the past 30-year window, the home team has won 56% of the time. You might remember, in the AL wild-card playoff, the host Royals rallied past the visiting A’s. You might also remember, in the NL wild-card playoff, the host Pirates got clobbered by the visiting Giants. A wild-card playoff isn’t like a late game in the World Series, but it’s still incredibly intense, and you’d figure if there were any effect it would show up. Those crowds are frenzied. Sometimes it feels like they make a difference. Almost half of the time, it doesn’t.

This is one of those things you probably don’t even need to research. It doesn’t stand up to general scrutiny. Every baseball game applies pressure, and every postseason baseball game applies a little more pressure. Why would there be something special about higher-leverage playoff games, in terms of the home-field advantage? Everyone’s going to be a little nervous, and a loud crowd isn’t going to help the home team forget about the stakes. If anything those fans might apply more pressure, with their demanding, expectant attitudes. Ultimately, a baseball game gets played, and it’s never been demonstrated that the game itself responds to the volume of the environment.

I mean, the Royals fans are going to be crazy in Game 6 and in a potential Game 7, but they were also crazy in anticipation of Game 1. First World Series game in Kansas City since 1985! The Giants scored the game’s first seven runs. They scored three times in the top of the first. There’s nothing meaningful there. One game is nothing but anecdotal evidence, but if you choose to believe the Royals will have a massive home-field advantage now, where was it in the series’ first game?

We’re left with very simple math. What are the Royals’ World Series odds? If you figure they and the Giants are even, and if you build in the small but real home-field advantage factor, then you’ve got 54% * 54%, which comes out to 29%. Our odds put the Royals at 26%, which tells you pretty much the same thing. The Royals need two good flips of the coin, and while the games won’t actually be determined purely by chance, it’s a perfectly fine way to look at it from here. Play this out 400 times, the Giants win something like 300 times. Around 200 times, we get a Game 7, and around 100 times, the Royals win that. The only way for the math to be any simpler is if Kansas City wins tonight. Then the whole season is nine innings, or more if baseball wants to give people heart attacks.

Tuesday and possibly Wednesday, the Royals are going to be backed by a vocal and incredibly supportive partisan audience. The Royals players will hear the noise, in between when they play baseball.