Two Cubs Hitters' Swing Speeds Are Trending in Opposite Directions Early On

There can be some value in early season statistics. Certain numbers can portend future success, or failure. Kyle Tucker only had two hits in his first 19 plate appearances? That stinks. I also don’t care. I won’t pretend to know for sure what kind of season Tucker will have, however, I am certain that he will finish with a higher batting average than .125. As Billie Joe Armstrong once sang, wake me up when September ends—or, in this case, when April does. Tucker busted right out of his pseudo-funk Saturday, anyway.

To me, one figure that is worth monitoring at this point is swing speed. Most everyday players for the Cubs have upwards of 20 competitive swings logged. Swing speed is not a statistic that allows outliers the ability to drag a player’s average swing speed down. Baseball Savant measures this by looking at the top 90 percent of a hitter’s swing speeds. If you look at swing speeds by month for the Cubs last season, almost all players' best and worst months, by swing speed, were within roughly 1 mph of each other. This seems to stay pretty consistent, which is what you'd expect. It's a lot like a pitcher's velocity. If it didn't stabilize quickly, that would be weird.

I mention this because Pete Crow-Armstrong is not only leading the Cubs in average swing speed, but increased his average swing speed from 70.6 mph in 2024 to 74.3 mph so far in 2025. His average exit velocity and hard-hit rate have followed suit. All stats courtesy of Baseball Savant:

Crow-Armstrong did have considerably more variance in his swings last season than most players. His fastest swing speed month was March/April, when he averaged 71.9 mph. His slowest was September/October, when he averaged 69.0 mph. Neither figure touches 74.3 mph, though, and even last April, his fast swing rate was all the way down at 17.5%. Last year, the young center fielder’s average swing speed of 70.6 mph placed him 169th of 214 qualified players. An average swing speed of 74.3 mph would have bumped him up to 28th, alongside players like Bobby Witt, Fernando Tatis, and William Contreras. 

Why is this important? The returns on exit velocity are well-known at this point. When you hit the ball harder, it goes farther and has a better chance of being a hit. This all starts with swing speed. Swing the bat harder, the ball comes off the bat at a faster speed.

For reference, Statcast's definition of a fast swing is any swing that is over 75 mph. According to Mike Petriello in his writeup about this last season, swings over 75 mph produced a .306 batting average and a .603 slugging percentage. Swings slower than that, taken together, produced a .247 batting average and a .371 slugging percentage. This uptick is (potentially) a huge development for a guy the Cubs really need to break out.

On the other side of the coin, Seiya Suzuki has an average swing speed of 71.2 mph, which is down from 73.0 mph last season. This, to me, is incredibly concerning, for someone who has suffered from injured obliques, a muscle that is very important to a hitter’s swing, at the beginning of the past two seasons. His average swing speed in March and April of last season (before his injury) was 72.1 mph, which was his lowest month of the season, but still a far cry from the 71.2 mph that it currently sits at. The gap is smaller here, though, and he's trending in the right direction over the last couple of games.

Perhaps Suzuki is a guy who really needs some time to warm up. Maybe he isn’t seeing the ball well and isn’t getting off good swings yet. Or maybe PCA stole his powers, like the Monstars in Space Jam. Either way, keep a close eye on the swings that these two get off in the next couple of weeks. Will Crow-Armstrong keep the quicker swings up, and will his performance take off as a result? Will Suzuki’s swings get back up to a more normal pace for him, or will his performance suffer?