About a week ago, Baseball Savant introduced the public to MLB players’ bat speed data as well as some other fun measurements of that analyze a player’s swing. Essentially, we now have the equivalent of Trackman data for pitchers but for hitters. Bat speed has been measured for years with the usage of DK bat sensors and Blast Motion sensors (and others) but this data has never been readily available to the public like it is now. New stats like Squared-Up%, which measures a player's ability to maximize exit velocity based on the speed of the swing itself, and Blast%, which quantifies the pinnacle of a baseball swing, one that is a “fast-swing” and one that qualifies as being “squared-up”. A fast swing is any swing that is 75 MPH or greater in speed. About 25% of players in the league average a swing that is classified as fast, per Baseball Savant. Swing length has also been introduced, which is pretty self-explanatory.
Now that we have the basics of this new data down, what can we do with it?
Above is a scatter plot that plots every MLB player with a minimum of 200 swings with the x-value being the player's average bat speed, the y-value being the player’s expected weight on-base-average, and the color of the plot resembling the player’s average exit velocity. This scatter plot proves that there is a slight correlation between xwOBA and bat speed but there is certainly a correlation between bat speed and average exit velocity.
This graph measures a player’s swing length vs. their success at the plate. As we can see, the creation is a bit more loose when it comes the swing length. Some players are able to generate a lot of power that in turn causes their xwOBA to rise, while other players who have long swings fall lower in the xwOBA department. We can conclude that a longer swing directly positively influences average exit velocity. It does the same for maximum exit velocity.
Shorter swings are generally thought to bring more contact and while these short swings aren’t classified as ‘fast’ they do result in more squared up contact. Luis Arraez has the slowest, but shortest, swing in all of baseball and he’s won back-to-back batting titles. Despite boor bat speed, Arraez has been the premium example of a contact bat.
Here is an example of a shorter swing length resulting in better contact. While the quality of the contact isn’t always great, the players towards the top right of the graph make contact more often and have shorter swings. The sporadic spread of colored plots suggests that we still haven’t quite been able to find a clear correlation between success and these new bat-tracking stats.
Bat-tracking can quantify how a hitter goes about an at-bat. We can more easily see things like approach, whether that be figuring out how someone changes their swing in a 2-strike count or if a player is more pull-happy.
The five players highlighted on this scatter plot of average bat speed and swing length are Isaac Paredes, Jeimer Candelario, Jose Altuve, Nolan Arenado, and Marcus Semien. Each of these players shares the same tendency, they pull the ball far higher than the league average. Altuve currently leads all qualified hitters with a 60.7% pull rate. All of them fall within the top 25 in Pull% except for Semien. However, since 2022, Semein is 13th in Pull%.
If we take a look at the whole picture, it paints a different story
These are the top pull-happy hitters in baseball (and our other 5 ‘top-left’ guys from earlier). Here, we can see that there isn’t as tight of a trend. This could be because we’re only a couple of months into the season and as time goes on things will shake out more clearly. One thing is certain, though. Every hitter on here with the exception of Spencer Torkelson has above average swing length.
Note that: being north of that red line suggests that their bat speed is above average
So we draw another conclusion, longer swing length does tend to equal more pulled balls.
We can also see that these pull-happy-long-swinging-sluggers see more success in terms of xwOBA but it’s been known that for the most part, a higher pull rate is related to success so this graph shouldn’t be too surprising.
Overall the average xwOBA of these players is: .328
The players who find themselves in the bottom right have below-average swing length and above-average swing speed. Logically, that sounds better. You’re getting to the ball quicker and faster. Let’s see if this is true.
I did a search to find players who have a swing that is 7.4 feet or shorter and a bat speed that is 73 MPH or greater, there were 11.
Each of these players, besides Alvarez and Burger, has an above-average xwOBA as it stands today. This group of players has an average xwOBA of .365! This is noticeably better than the previous group. This was once again, expected. There’s far too much vulnerability in players who rely on their batted ball location rather than their swing in itself.
So if a longer swing generates a higher average exit velocity but a longer swing can result in worse results, what happens to the guys with elite bat speed but long bat paths? There 7 players with a minimum of 200 swings who have a swing length greater or equal to 7.8 feet and an average bat of at least 74 MPH.
This group is headlined by the hottest hitter in baseball right now, Aaron Judge. Whenever Judge is involved, it’s important to remember that he is an alien and incomparable to the average (or even above average) big leaguer when it comes to plate skills. These guys listed are power hitters through and through. Even Jordan Walker, who is currently back down in AAA after starting the season with a 46 wRC+ for St. Louis. A large reason for his demotion was due to a 26.9% K-rate that Walker was sporting. In fact, all of these guys are known to strike out, even Judge. Javy Baez made his way into this group and he’s been one of the worst-qualified bats in baseball since signing with Detroit. Stanton, Soler, and Schwarber are big-time power hitters who go through their wicked hot streaks but can also look like a liability when their out of tune at the plate due to the amount of swing and miss they generate.
The longer swing typically leads to more chance for whiff, even when the bat is getting there at a higher speed. All in all, these ‘Top Right’ guys shake out to produce an average xwOBA of .347.
The group headlined by the biggest outlier of the entire bat-tracking universe, Luis Arraez, is up last. These guys fail to generate solid bat speed, however, they do a good job of getting their bat to the ball.
This scatter plot is much harder to read because, well, more of these guys fall in the same tier of production. This was the section of the Statcast graph that I was most interested for in terms of overall production. Heads up, it’s not pretty. This group averages together for a .288 xwOBA.
Now, remember a couple of things;
- It is May 20th at the time of this article
- There are a number of outliers that find themselves nustled into sections of the graph that greatly improve or worsen their overall stats.
However, from this study, it does look like you absolutely, positively, do not want to be in the bottom left of this graph. While the bottom left seems to be the ‘dead zone’ for hitters, the top right, its total opposite, is not the best place to be. That title goes to the hitters in the bottom right, the fast and short guys.
With the help of Baseball Savant’s search engine and Python’s Pandas, I’ve filtered through a number of files to figure out who in the big leagues has the biggest change in approach when they’re ahead or behind. First up, let’s start with the cautious players. The following players have the biggest decrease in bat speed when they’re behind in the count.
Some notable names include Luis Robert Jr., Xander Bogaerts, and Seiya Suzuki. Luis Robert Jr. has by far the biggest difference between his A swing and his B swing.
Check that… it looks like Robert Jr. has three different swings. This is a very small sample size of about 30 plate appearances but there does still seem to be a clear effort in change of approach. This likely won’t look the same once we get a larger crop of data from Southside’s centerfielder but it will be something to keep an eye on. If we change the parameters to make the sample size larger, the list looks like this:
Now, Harold Ramirez is the king of changing his two-strike approach. Bader, Herrera, and Conforto aren’t too far behind him. Here’s what their swing distribution charts look like one on top of another:
Conforto has the clearest difference, that valley in between the peaks of his distribution is the most notable of this bunch. An important name on the list of players who significantly drop their bat speed when they’re in 2-strike situations is Shohei Ohtani. There are plenty of hitters who are elite in two-strike counts who aren’t on this list but seeing him on this list is very interesting.
The average xwOBA for this group of guys is .322. That with Ohtani.
The final group of players we’ll look at is the ones without a clear ‘B’ swing. These players go up with the same bat speed each and every pitch no matter the count. This sounds like a poor plan but we’ll see if they find more or less success than the hitters who change their approach on a situational basis.
These players have a very consistent approach at the plate. The difference in average bat speed for the top of this list is honestly unbelievable. A 0.005 MPH change in average bat speed in a 2-strike situation is certainly something. Here’s what the top 4 hitters on this list’s distribution chart looks like:
All in all the 20 smallest difference in swing speed’s average xwOBA comes out to .315. That difference is much, much closer than I was expecting but examining this on a player-to-player level would likely yield more contrasting results, rather than averaging everything out.
For fun, here’s a list of players who’s bat speed INCREASES when they get into a two-strike count.
I find Miguel Sano the most interesting here. He has the highest bat speed of any other player listed and he chooses to increase it when he’s facing the chance of striking out. It’s interesting to see Brice Turang on this list, Turang has been known as a contact bat since debuting last season but it appears that he gets a boost of bat speed when behind. Seeing Jose Siri on this list makes me nervous to see the average xwOBA totals for this group. The power/speed-tooled outfielder has struggled in the department of plate discipline over the last few years.
These 20 players average together for an xwOBA of .297… yikes. I can’t say I’m surprised.
All in all, this data is fun and it’s really cool. Having access to this kind of stuff is extraordinary and widens the possibilities for baseball research further than it’s ever been.
However, I don’t think that the graph above really matters all too much. I’d much rather use this data to try and suggest a change in a specific hitter’s approach like a Jazz Chisholm Jr. or a Jacob Young, both of which struggle to change their swing when they get behind in the count. It’s fun to poke and prod around with this data, yes, but the x-y graph doesn’t show much correlation in success, at least from what I’ve found.
Happy Bat-Tracking and thanks for reading!
