Yesterday, the Royals made a giant announcement. Kauffman Stadium, lengthy some of the cavernous venues within the majors, goes to be rather less warehouse-like this yr. The partitions are shifting in 9 or 10 ft roughly throughout the board, and getting shorter by a foot and a half as well. That’s a significant change for a stadium the place residence runs typically go to die. How huge? Time to crank up the outdated laptop and discover out.
I plugged the brand new dimensions from Kansas Metropolis’s press launch into an equation describing a tough arc. I match these factors to a cubic spline in order that it might extra intently resemble the precise stadium, with its pinched-in corners. I made just a few approximations as properly; as an example, the wall is shifting to a top of eight and a half ft “in most locations,” so I simply utilized that throughout the board. I additionally modeled the outdated dimensions the identical manner. That manner, I had two completely different digital partitions constructed to match some batted ball information in opposition to.
Notably, my approximation isn’t an ideal duplicate of the stadium. I don’t have a millimeter-scale, or perhaps a yard-scale, map of the place. I can’t account for outfielders robbing residence runs, which is certainly going to be extra frequent with the lowered partitions, although nonetheless fairly uncommon total. However by working it by each the outdated and new wall dimensions, I believe that this unavoidable error may be minimized. It’s fairly clear that no balls that had been residence runs with the outdated outfield parameters will instantly not be residence runs with the brand new ones, so the factor we’re in search of is the distinction, assuming that my approximation is shut sufficient to actuality. And it’s: My modeling says that over the past three years respectively, 205, 162, and 159 batted balls hit in Kansas Metropolis ought to have become homers. In actuality, it’s been 186, 147, and 151.
My estimates run somewhat scorching, in different phrases, however they’re very constant. A visible inspection of the batted balls that had been misclassified is generally a pile of extra-base hits off the wall, just a few strange-angled blasts that trick my trajectory-smoothing mannequin, and some leaping catches. Any of those will certainly flip into homers with the brand new dimensions. So long as we’re simply utilizing this mannequin to have a look at adjustments, I really feel very snug with it, and actually it could barely underestimate the rise in residence runs.
With that mentioned, let’s get to the info. I in contrast each batted ball from 2025 to each units of wall coordinates and recognized 43 new residence runs within the new configuration:
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I ran the identical check for yearly now we have Statcast information for – in spite of everything, with the partitions already just about constructed, I can throw loads of completely different batted ball units at it with out a lot effort. The typical enhance in homers over the previous 10 years (excluding the shortened 2020 season, a sentence I’ll in all probability must preserve writing ceaselessly, like Sisyphus) was 51 per season. That’s a chunky enhance, and with 9 of the ten values between 40 and 60 (2023 had a 70-homer enhance within the power-happiest precise yr of Kauffman information), I really feel fairly assured within the measurement of the impact.
What sorts of batted balls have become residence runs? Probably the most useful ones you may probably think about, principally. Kauffman is large. A lot of the 43 batted balls that I labeled as in play in 2025 however residence runs in 2026 landed safely for hits even with the outdated dimensions. They’d a median wOBA of .943, with a .700 BABIP. They had been missiles, principally; balls hit at splendid residence run angles, liners and fly balls shot over the top of outfielders with no probability of attending to them however held in by the enormous park. So 43 new homers isn’t 43 extra hits – it’s extra like 43 new homers, 13 fewer outs, and 30 fewer doubles and triples.
Need to see the place the brand new homers would land? Nicely, in every single place:
The explanation that not one of the dots are proper on the new wall is that it’s a must to clear it, and the distances I’m utilizing are projected touchdown factors. However you get the concept; pull the partitions in in every single place apart from heart, and also you’re going to get a ton extra residence runs in every single place apart from heart. The few straggling dots within the center are the odd beneficiaries of the decrease partitions.
What is going to this do to run scoring? I can hazard a guess, although it’ll nonetheless simply be a guess till we see precise video games within the new dimensions. Swap in, say, 50 new homers (a pleasant spherical quantity near the typical enhance from above), swap out the combination mixture of doubles, outs, and triples that they “used” to be, and also you get a rise in whole run scoring of 57.2 runs throughout 81 residence video games. That’s for each groups, after all, since I used each batted ball to bulk up the pattern measurement. That’s an additional .35 runs per group per sport, nonetheless a significant increase. Even after paring that down considerably on the belief that fielders will do higher on the remaining balls in play because of having a smaller space to cowl, that’s nonetheless an enormous raise.
Whereas Kauffman has lengthy been one of many worst stadiums in baseball for residence runs, it wasn’t an offensive wasteland. Park elements put it round impartial total. Final season was truly the primary yr since 2019 the place the Royals scored extra runs on the street than at residence. That doesn’t imply it’s wildly offense-friendly — residence subject benefit exists — however a lot of completely different park issue approximation strategies independently peg the stadium as roughly common total. Add 0.3 runs to every group every sport, and even 0.25 in case you actually suppose that BABIP will decline a ton because of the smaller dimensions, and we’re speaking one of many friendlier stadiums within the league for offense.
After all, the precise impact on scoring shall be extra nuanced and seasonal than my broad re-classification of batted balls. Dr. Daniel Mack, the group’s vice chairman of analysis, defined among the extra elements the group thought of when making the change: “(Senior analyst) Alan (Kohler) and I began breaking it down. What’s the impact of the partitions? What’s the impact of the altitude? What’s the impact of the temperature and wind? Making an attempt to determine find out how to take all these results under consideration and stability them.” Kauffman doesn’t play the identical yr spherical; Kansas Metropolis has large variance in climate all year long, with meaningfully altering air resistance and wind patterns. The stadium performs in a different way in April than it does in July, one thing I didn’t even try to mannequin in my fast take. However averaged throughout the yr, I believe the rise in scoring is not less than within the realm of what’ll occur, including sufficient residence runs to greater than take the sting out of the misplaced doubles.
I may not have the precise week-to-week fluctuations down, however the information continues to be ok to make some predictions. I first famous which gamers would have seen the biggest will increase in Kauffman residence runs with the brand new dimensions. Maikel Garcia’s 2025 batted balls would have produced 5 extra homers with the brand new partitions, per this estimation, whereas Jonathan India would additionally see his homer whole enhance by 5. Salvador Perez’s would enhance by 4, with Vinnie Pasquantino’s and Bobby Witt Jr.’s going up by three apiece.
We are able to go additional again. Right here’s a leaderboard of profession homers “gained” within the alternate universe the place Kauffman at all times had smaller dimensions:
Most Dwelling Runs “Gained” If New Dimensions Had Began in 2015
And, naturally, a leaderboard of the pitchers who would have suffered probably the most. I’m shocked that Yordano Ventura is on there with solely two seasons of knowledge, however he occurred to surrender a ton of not-quite-homers in these two years:
Most Further Homers Allowed if New Dimensions Had Began in 2015
Whereas the magnitude could be unsure, the course of the change is obvious. The brand new stadium dimensions are going to make for meaningfully extra residence runs. That’s very a lot on objective. As Mack detailed to Jeff Passan, the aim of this transformation in dimensions was to provide a league common run worth on fly balls within the park. Whereas Kauffman performs like a roughly impartial park total, it significantly suppresses residence runs whereas juicing doubles and triples.
Fly ball run worth has traditionally been low in Kaufmann as a result of a disproportionate quantity of that worth comes from homers, whereas the additional doubles and triples have juiced the worth of line drives. That doesn’t mirror the incentives in each different stadium within the majors, and this transformation addresses that straight.
Nicely, form of straight. The brand new dimensions undoubtedly assist fly balls. By my estimation, 24 fly balls that didn’t go away Kauffman in 2025 would have been residence runs with the brand new partitions. However 19 line drives that didn’t go away the park in 2025 would have gone out as properly. Now, to make certain, the road drives had been way more productive than the fly balls with the outdated wall configuration, so the improve to fly ball worth is actual. However line drives are getting extra useful, too. And whereas the brand new dimensions will cut back the realm outfielders must defend, Kauffman will nonetheless boast meaningfully extra outfield sq. footage than common, so the times of gappers and velocity are hardly over.
Will Bobby Witt Jr. mash a trillion residence runs in 2026? Will the Royals change into the brand new scorching offense in KC with Patrick Mahomes on the shelf and the Chiefs in a quick downturn? We gained’t know till they play the video games. However Kauffman has at all times been extra offense-friendly than the spacious dimensions would recommend, a form of mini-Coors. Pull the partitions in, and we might be in for some enjoyable slugfests. I hope the Pasquatch has been doing his cardio.
