Royals Review Laboratory: What makes Kauffman Stadium a neutral park?

In the opening salvo for the series, we give the worm to the early bird, the first email we received from emailer John.

I noticed Kauffman is generally listed as a neutral park (hitter v. pitcher). I’ve always believed it is a pitcher’s park, but the Royals had such bad pitching for so long that the numbers skewed more to the middle as a result. If you can look into it I’d greatly appreciate it!

Thanks!

This is definitely an often disconnect you hear vs what you read. Now John mentions that perhaps it’s the Royals pitchers that skew those numbers, but we should quickly go over how park factors work, via FanGraphs:

For example, if a player has a .340 wOBA, but their home park is hitter friendly, they we need to adjust their wOBA down as a result. We don’t calculate a wOBA+, but some do. Instead, we jump over to wRC+ for our park adjusted offensive metric. This stat, among other things, applies a park adjustment to the player’s batting line. Stats like ERA- do this as well, and pretty much any time you see a +/- stat, it’s park adjusted.

And our park factors are applied with the additive method, meaning that we’re essentially adding or subtracting a little production based on how much offense is affected by the park in our estimate, but remember that we only apply half of the full park factor because a player only plays at home for half their games. We assume the rest are played in a pretty average setting.

As FanGraphs points out, we care about both a pitcher/hitters home and away games, to get a full view, so unless a pitcher is just bad at home and bad away, it will all be fixed in the numbers from the high level view. So park factors should notice a team pitches well at home but bad away and then see that something is probably helping them.

For now, let’s look at the park factors for Kauffman Stadium we can find (typically 1 or 100 is average):

FanGraphs: 101 (5yr), 102 (3yr), 103 (1yr)

Rotographs: 1.02

ESPN: 1.06

Fantasy Pros: 1.05

Baseball Prospectus: 100

Baseball Reference: 101

By all sources, Kauffman Stadium is at a minimum neutral, with a few sites leaning towards hitter friendly/pitcher unfriendly. But we always hear about Kauffman being a good pitchers park, which is both true and not.

Some things that should pop out to you:

At one time in the early 2000s, Kauffman was firmly a hitters park after the fences were moved in in 1995. In 2004 though, they were moved back, and a the area behind home plate was reduced slightly. Then of course in 2009 came the big aesthetic renovations that also saw left and right centerfield move back an additional two feet.

As you would expect, the fence moves in 2004 killed home runs in the park, a full 14 point swing from peak to trough (2000 to 2006), making Kauffman now one of the worst home runs parks in baseball.

So we know that Kauffman Stadium is where fly balls go to die in the American League, so what makes up all that ground? Kauffman has historically been very good for hits outside of home runs. Even though it compressed a bit in the early-00s, once the walls were moved back it became a semi-hitters paradise for singles, doubles, and triples. This is due to Kauffman have one of the largest in play areas in baseball:

Calculations per Scott Bailey

30% of the time in 2018, when any batter at Kauffman put a ball in play (including home runs) it went for a single, double, or triple. That’s amongst the top five rates in the league by venue.

Another way to look at it is that just 35% of all home runs allowed at Kauffman were under 400 feet, the 2nd lowest rate in the league. Meaning to hit a home run at Kauffman, 65% of the time you needed to hit it further than 400 feet, as opposed to Houston where you only needed to hit the ball 400+ feet for a homerun 32% of the time.

Looking around the league, the distribution for parks and their respective overall factors aren’t even either.

There are more neutral to pitcher friendly parks than hitter friendly parks.

On aggregate, the NL East is the “easiest” division to pitch in and the NL West is the hardest when you look at park factors. This perhaps challenges the notion that the AL East is the toughest environment to play, when it really isn’t much more challenging than the NL or AL Central.

Now John also asks about the Royals pitchers, and I’m here to tell you that last year the Royals pitchers just give up home runs regardless of where they played:

2018

Home: 102 allowed

Away: 103 allowed

But it varied in the prior years

2017

Home: 86 allowed

Away: 110 allowed

2016

Home: 91 allowed

Away: 115 allowed

2015

Home: 68 allowed

Away: 87 allowed

So something was in the water in 2018 that caused all the home runs to be allowed regardless of geography. And by something I mean baseballs and by water I mean the various fountains and pools across major league stadiums that Ian Kennedy, Danny Duffy, and Jake Junis played in.

As an ancillary thought, how about how Royals hitters fared home and away in regards to hits?

2018

Home: 456 1B 157 2B 18 3B 67 HR

Away: 427 1B 126 2B 11 3B 88 HR

2017

Home: 463 1B 135 2B 13 3B 88 HR

Away: 496 1B 125 2B 11 3B 105 HR

2016

Home: 513 1B 148 2B 23 3B 64 HR

Away: 493 1B 116 2B 10 3B 83 HR

Year in and year out, Royals batters hit more home runs away from Kauffman and more 1B/2B/3B at Kauffman.

Now maybe this is an answer for an entirely different question/article, but how do opposing hitters do at Kauffman for home runs?

2018

Royals: 67 HR

Opponents: 103 HR

2017

Royals: 88 HR

Opponents: 86 HR

2016:

Royals: 64 HR

Opponents: 91 HR

2015

Royals: 62 HR

Opponents: 68 HR

2014

Royals: 43 HR

Opponents: 59 HR

So typically, Royals opponents have out-homered them, often by a fair margin. That speaks to mainly the Royals roster construction than the park.

In summary, Kauffman plays down home runs heavily, but plays up doubles and triples while being neutral to singles. It’s pretty poor for batters hitting infield fly balls given all the room it has. You would also think that since there is decent foul ball area given the overall size of the field of play, strikeouts would be more since there is more room for foul balls that would otherwise be in play at other stadiums (like Fenway).