Yesterday, the Royals made an enormous announcement. Kauffman Stadium, lengthy one of the cavernous venues within the majors, goes to be rather less warehouse-like this yr. The partitions are shifting in 9 or 10 toes kind of throughout the board, and getting shorter by a foot and a half in addition. That’s a significant change for a stadium the place residence runs usually go to die. How large? Time to crank up the outdated pc and discover out.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 may extra intently resemble the precise stadium, with its pinched-in corners. I made just a few approximations as effectively; for example, the wall is shifting to a top of eight and a half toes “in most locations,” so I simply utilized that throughout the board. I additionally modeled the outdated dimensions the identical means. That means, I had two totally different digital partitions constructed to check some batted ball information towards.
Notably, my approximation isn’t an ideal reproduction 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 widespread with the lowered partitions, although nonetheless fairly uncommon general. However by operating it by means of each the outdated and new wall dimensions, I believe that this unavoidable error could be minimized. It’s fairly clear that no balls that have been residence runs with the outdated outfield parameters will abruptly not be residence runs with the brand new ones, so the factor we’re searching for is the distinction, assuming that my approximation is shut sufficient to actuality. And it’s: My modeling says that during the last three years respectively, 205, 162, and 159 batted balls hit in Kansas Metropolis ought to have was homers. In actuality, it’s been 186, 147, and 151.
My estimates run a little bit sizzling, in different phrases, however they’re very constant. A visible inspection of the batted balls that have 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 take a look at adjustments, I really feel very comfy with it, and in reality 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 take a look at for yearly we have now Statcast information for – in any case, with the partitions already nearly constructed, I can throw a whole lot of totally different batted ball units at it with out a lot effort. The typical improve in homers over the previous 10 years (excluding the shortened 2020 season, a sentence I’ll most likely must preserve writing perpetually, like Sisyphus) was 51 per season. That’s a chunky improve, and with 9 of the ten values between 40 and 60 (2023 had a 70-homer improve 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 was residence runs? Essentially the most helpful ones you’ll be able to presumably think about, principally. Kauffman is enormous. A lot of the 43 batted balls that I categorised as in play in 2025 however residence runs in 2026 landed safely for hits even with the outdated dimensions. That they had a mean wOBA of .943, with a .700 BABIP. They have been missiles, principally; balls hit at perfect residence run angles, liners and fly balls shot over the pinnacle of outfielders with no likelihood 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? Properly, in every single place:
The rationale that not one of the dots are proper on the new wall is that you must 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 middle, and also you’re going to get a ton extra residence runs in every single place apart from middle. 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 common improve from above), swap out the combination mixture of doubles, outs, and triples that they “used” to be, and also you get a rise in complete 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 staff per sport, nonetheless a significant enhance. Even after paring that down considerably on the belief that fielders will do higher on the remaining balls in play due to having a smaller space to cowl, that’s nonetheless a large elevate.
Whereas Kauffman has lengthy been one of many worst stadiums in baseball for residence runs, it wasn’t an offensive wasteland. Park components put it round impartial general. Final season was truly the primary yr since 2019 the place the Royals scored extra runs on the highway than at residence. That doesn’t imply it’s wildly offense-friendly — residence subject benefit exists — however quite a lot of totally different park issue approximation strategies independently peg the stadium as roughly common general. Add 0.3 runs to every staff every sport, and even 0.25 in case you actually assume that BABIP will decline a ton due to the smaller dimensions, and we’re speaking one of many friendlier stadiums within the league for offense.
After all, the precise impact on scoring will probably be extra nuanced and seasonal than my broad re-classification of batted balls. Dr. Daniel Mack, the staff’s vice chairman of analysis, defined a few of the further components the staff 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? Attempting to determine how you can take all these results into consideration and steadiness them.” Kauffman doesn’t play the identical yr spherical; Kansas Metropolis has enormous variance in climate all year long, with meaningfully altering air resistance and wind patterns. The stadium performs otherwise in April than it does in July, one thing I didn’t even try and mannequin in my fast take. However averaged throughout the yr, I believe the rise in scoring is at the very least 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 remains to be adequate to make some predictions. I first famous which gamers would have seen the most important 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 complete improve by 5. Salvador Perez’s would improve by 4, with Vinnie Pasquantino’s and Bobby Witt Jr.’s going up by three apiece.
We will 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 route of the change is evident. 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 supply a league common run worth on fly balls within the park. Whereas Kauffman performs like a roughly impartial park general, it enormously 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.
Properly, type of straight. The brand new dimensions positively assist fly balls. By my estimation, 24 fly balls that didn’t depart Kauffman in 2025 would have been residence runs with the brand new partitions. However 19 line drives that didn’t depart the park in 2025 would have gone out as effectively. Now, to make sure, the road drives have 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 helpful, too. And whereas the brand new dimensions will cut back the world outfielders must defend, Kauffman will nonetheless boast meaningfully extra outfield sq. footage than common, so the times of gappers and pace are hardly over.
Will Bobby Witt Jr. mash a trillion residence runs in 2026? Will the Royals turn into the brand new sizzling offense in KC with Patrick Mahomes on the shelf and the Chiefs in a short downturn? We received’t know till they play the video games. However Kauffman has at all times been extra offense-friendly than the spacious dimensions would counsel, a kind of mini-Coors. Pull the partitions in, and we could possibly be in for some enjoyable slugfests. I hope the Pasquatch has been doing his cardio.