The last two seasons have been the two most homer-happy seasons in baseball history. Over the 2019 and 2020 seasons, a baseball has left the yard once every 27.9 plate appearances. Just a bit over six years ago, when the Royals were hoisting the championship trophy, a home run was hit once every 37.4 plate appearances. Even at the height of the performance-enhancing drug era, a home run was hit once every 33.4 plate appearances. It is pretty clear to anyone watching the game - baseballs are leaving at an unprecedented rate.
Home run rates are up, in part, due to an emphasis on exit velocities, launch angles, and a greater acceptance of the “grip-it-and-rip-it” hitting philosophy. There is some evidence that alterations in the ball may be contributing and a study by MLB concluded that higher seams causing less drag may have had a marginal impact. With pitchers complaining of a “juiced ball” and some fans arguing that there are too many home runs, MLB has decided that it can counteract a rise in home run rates by “deadening” the ball.
According to a report in The Athletic by Ken Rosenthal and Eno Sarris, baseball has sent out a league-wide memo highlighting slight changes to the ball that should be expected to cause a decline in home run rates this year. The changes should reduce the weight of the ball by less than one-tenth of an ounce, and slightly decrease the bounciness of the ball.
MLB would not be the first league to try to deaden the ball to depress home run rates. The KBO in Korea altered their ball before the 2019 season, with major impacts on offense. Home runs fell from 1.23 per game to 0.71. Runs per game fell a full run. Batting averages fell from .286 to .267, but strikeouts fell as well, from 18.7 percent to 17.2 percent, perhaps as hitters focused more on making contact.
MLB may not realize the same effects, since they are decreasing the weight of the ball, while the KBO actually increased the weight of the ball, which increased drag. As astrophysicist Dr. Meredith Wills put it, “Unless a decrease in weight can be offset so as not to make the ball smaller, you might expect drag to go down here, leading to the odd situation of a ball that is deader coming off the bat but carries farther.”
An MLB study found that fly balls that went over 375 feet lost one to two feet of batted ball distance, and The Athletic article cites an analyst that estimates home run rates will drop five percent with a new ball. A five percent drop in home run rates from last year would still be one of the highest home run rates in baseball history. Home run rates would have to drop about 25 percent just to get to 2015 levels.
So that is probably not enough to impact how teams operate, although we can’t be certain what the impact will be. The article also mentions that ten teams will be storing baseballs in humidors this season, which could drop home run rates as much as 20 percent in those stadiums.
If we do see a significantly reduced home run rate, how might it impact the Royals? The home run spike has not been as pronounced at Kauffman Stadiums with the number of home runs going from 0.793 per game in 2015 to 0.87 per game last year - less than a ten percent increase. A deadened ball could help them more on the road, where a lack of power has caused them to have trouble in slugfests.
A true reduction in home run rates could help some flyball pitchers like Danny Duffy and Jakob Junis, who have had trouble keeping the ball in the ballpark the last two seasons. It could make Jorge Soler more valuable if home runs aren’t as cheap, and he has the kind of power that can blast the ball out of the ballpark regardless of the ball. If the game moves more to players that can make contact, it could make Whit Merrifield more valuable as well.
The Royals are also trying to develop a group of young pitchers, and avoiding an era in which any pitch out over the plate can be knocked over the wall can help them learn to trust their stuff. On the other hand, a deader baseball could hurt a hitter like Salvador Perez, who has good power, but could lose a few home runs if the ball isn’t traveling as far.
Is baseball right to deaden the ball? The long ball has been revered throughout baseball history, but there can be too much of a good thing. A game that relies too much on the “three true outcomes” - home runs, walks, and strikeouts - is a game with less action. Deadening the ball is only one part of the equation. MLB will have to do something about the spike in strikeout rates as well - perhaps lowering the mound - or else this will just lead to lower scoring strikeout-fests.
Still, this looks like a step in the right direction.