Kauffman Stadium: Pitcher-Friendly, Hitter-Friendly

This October, there’s been a lot of talk about the Royals’ offense, which is a very unexpected sentence. By now everyone should be pretty familiar with the Royals’ approach: they try to hit the ball and make things happen, as opposed to sitting back and waiting for dingers. At a few points, you might’ve read remarks along these lines from Royals officials: if the team played in a different ballpark, they’d hit a lot more homers. This year the Royals were actually last in the American League in road home runs, so it’s not like dimensions have conspired to suffocate a juggernaut, but the bigger message is that the Royals have a big stadium. And Kauffman Stadium, indeed, is statistically tough on the longball.

Let’s play an assumption game for some reason. Say you’re given only one piece of information about a stadium, and from there you have to guess how the stadium plays overall. By our numbers, Kauffman Stadium has baseball’s seventh-lowest home-run factor. That means it’s probably pitcher-friendly, right? AT&T Park is pitcher-friendly. PNC Park is pitcher-friendly. Safeco, historically, has been pitcher-friendly. But this is the interesting twist, at least as far as park factors go: Kansas City’s ballpark is overall hitter-friendly. It’s just not so in the ordinary way.

You can look at this in a few places. By the FanGraphs numbers, Kauffman’s home-run factor is 94, where 100 is average. That puts it between Target Field and Angel Stadium. Yet the overall run factor is 101, equal with Great American Ball Park and just a point behind Camden Yards. Meanwhile, StatCorner offers its own park factors, broken down by handedness, and that site also sees the dinger reduction, and the overall offensive boost. Splitting parks by handedness, we can look at 60 different factors. Both of Kauffman’s home-run factors rank in the bottom 25%, but both of the run factors rank in the upper 35%. Clearly, there’s something a little unusual happening here, since there’s nothing more impactful from the offensive side than a homer.

So how does Kauffman manage to be both pitcher-friendly and hitter-friendly? The answer’s actually pretty intuitive, and it has to do with the same stuff we talked about when a few teams were bringing the fences in in the recent past. When you move in the fences, you make homers more likely, but you also shrink the outfield. When the fences are far away, the outfield’s bigger, and here’s a relevant recent excerpt from the USA Today:

But the bigger gaps – the Kauffman outfield has the most square footage in the majors – favored the Orioles early.

I don’t buy that, exactly — I’m pretty sure Coors Field is bigger. But Kauffman’s still big, seemingly the biggest yard in at least its own league. More space means fewer homers, but it also means a lower percentage of space that can be covered by defenders. Which means more baseballs reaching more grass, which means more hits, which — I don’t have to explain this to you.

Have you ever messed around on Clem’s Baseball? I’d recommend it, if you’re into this stuff, and that site backs up the idea that Kauffman Stadium has the most square footage in the outfield in the American League. The dimensions down the lines are basically average, but to left-center, Kauffman’s more than a full standard deviation deeper than average. It’s even deeper, relatively speaking, to right-center, and center’s still 410 feet away, against an average of 404. Kauffman’s a spacious place. The Royals have known this for years. It’s probably not a coincidence the team has been built as it has.

The dimensions leave a statistical signature. Over the last five years, there have been 773 home runs in Royals home games, and 910 home runs in Royals road games. However:

Runs scored

Royals home games: 4,325
Royals road games: 4,162

Batting average on balls in play

Royals home games: .307
Royals road games: .298


Royals home games: .323
Royals road games: .318

The FanGraphs numbers show Kauffman with an above-average singles factor, an above-average doubles factor, and a well above-average triples factor. As a different way of thinking about this, we can pull a little data from Baseball Savant. This year, in Royals home games, 21% of balls in play hit at least 300 feet went for homers. On the road, that rate was 26%. However, in Royals home games, 40% of balls in play hit at least 300 feet went for singles, doubles, or triples. On the road, that rate was 32%. That’s just one year of information, but it conveys the right idea. Home runs and hits can be negatively correlated.

There’s also a little bit more. You might notice that Kauffman has a below-average pop-up factor. It’s about as far removed from average as Oakland’s pop-up factor. Kauffman Stadium has a below-average amount of foul territory, in terms of square feet, and its backstop is closer to the plate than it is in most stadiums. So, over the last five years, Royals home games have featured a pop-up rate of 9.1% on fly balls, and Royals road games have come in at 10.9%. This is a small thing, but pop-ups are automatic outs, and pop-ups that drift into the seats are just strikes.

And finally, you’ll notice that Kauffman Stadium appears to reduce strikeouts, without reducing walks. It’s not quite Coors Field in that regard, but Coors is a freak, and the Kauffman note is interesting. Again, over the last five years, the home-game walk rate and the road-game walk rate have been even, around 8%. But Royals home games have had a strikeout rate under 17%, and Royals road games have had a strikeout rate over 18%. Strikeouts are also automatic outs, so Kauffman has for whatever reason encouraged more balls in play, and those balls in play have also been more likely to find the ground than they have been in other places. In one way, one very significant way, Kauffman has played difficult for hitters. In a variety of other ways, it’s more than balanced that out.

Kauffman isn’t alone like this. Target Field seems overall fine for offense, but bad for homers. The same goes for Marlins Park. Both seem like pretty good environmental comparisons, with Marlins Park in particular offering more square footage to compensate for the deep fences. When you think about it in depth, it makes all the sense in the world. But when you just consider it briefly, it’s odd. Not a lot of homers hit in Kansas City. Still plenty of runs, though, at least relative to the games played elsewhere. In large part because of all this, Dayton Moore assembled a rangey group of outfielders. In large part because of all this, the Royals’ defense looks worse by raw BABIP than it would if you adjusted it. Ballparks are complicated things, in the ways that they play, and Kauffman Stadium is one environment where pitchers might feel comfortable, while hitters feel comfortable too. Damage still gets done. It’s just relatively gentle.

Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

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Jim S.
7 years ago

Excellent stuff, Jeff. As usual.