Earlier in the season, Statcast unveiled their new bat tracking data, which gave us a handful of new leaderboards. Here at Rotoworld, we broke down all those metrics with James Schiano looking at Blast Rate, Matthew Pouliot digging into Squared-up Rate, and me looking into bat speed and swing length, and also hitters who change their swing with two strikes. If you're unfamiliar with these stats, I encourage you to check out those articles as a kind of primer.

However, now that we have multiple months of that data, I wanted to see if we could learn anything from looking at month-to-month changes.

On the surface, it makes sense that a player whose bat speed is slowing from one month to the next might be struggling. It makes sense that a player whose swing is getting shorter might be making more contact. But is that actually true?

In order to do a cursory check, I took all the June data and May data and looked at whose bat speed had sped up or slowed down the most, who was squaring the ball up more, etc. I kept it to hitters who qualified for season-long leaderboards because we wanted enough swings to use as a comparison, and I tried to use a broad brush in my analysis here. As a result, we're not digging into the nitty gritty details, but trying to more globally see if changes in one direction or another can tell us more about a player's performance than we might already know.

My hope is that looking into this will give us a little better insight into how to use these new metrics and if they can add another level to our analysis as we get more in-season data. Let's all find out together how that went.

June Bat Speed Gainers

This list is interesting because quite a few players on here are having great months but a few players are struggling in June.

We tend to equate bat speed with power, and there are a few names on this list who have improved in that regard from May to June. Pete Alonso has a .846 OPS in June with a .231 ISO after posting a .732 OPS in May with a .206 ISO. He's not really pulling the ball or lifting the ball more or less, and his hard-hit rate actually spiked most in the final weeks of May, but he's been hitting the ball harder more consistently in June. Yordan Alvarez has seven home runs and a 1.117 OPS in June after hitting two home runs and posting a .776 OPS in May. J.P. Crawford has hit four home runs in June after hitting just one in May, and Kyle Schwarber has six home runs in June after hitting just three in May.

Jose Altuve also had just a .573 OPS in May with a .068 ISO and now has a .861 OPS in June with a .165 ISO. Same goes for Jonathan India, who had a .669 OPS in May with a .110 ISO and now has a .990 OPS in June with a .181 ISO. Those are big improvements, and other hitters like Paul Goldschmidt, Byron Buxton, MJ Melendez, Amed Rosario, and Ketel Marte are enjoying better months in June, so the vast majority of hitters on this list have seen some uptick in their production to go along with the quicker bat speed.

But not all of them.

Wilyer Abreu has played in just six games while battling an injury and is not hitting well in June, so his presence on this list is a bit confusing. Brent Rooker is also hitting just .208 in June with three home runs after hitting .330 with six home runs in May. He's also striking out about 40% of the time, so his quicker bat speed is doing nothing to improve his hitting. Same goes for Mitch Haniger, who's hitting just .192 in June with no home runs and has seen his ISO dip to .056.

Perhaps it's not a bad sample size that just three of 15 players have been worse despite a quicker bat, but it's enough to make us understand that bat speed improvement doesn't guarantee success in the batter's box. We'll see more of that below.

June Bat Speed Decliners

While many of these guys are having rough months, it's interesting to see that Juan Soto and CJ Abrams are in the top five in reduced bat speed because they're both enjoying solid months. Soto's ISO has been worse in June and he has just four home runs compared to seven in May, but his OPS is up, and he's hitting the ball well. Perhaps, the lower bat speed is connected to the fact that Soto's pull rate has dropped from 58.3% in May to 41% in June. Considering he's still hitting the ball hard, my guess is that pitchers are keeping the ball away from Soto, which has led to him pulling less, which has caused the bat speed rating to show a decrease because he's not having to turn on pitches as often.

CJ Abrams is also having a much better month all across the board and is pulling the ball the exact same amount from May to June, so that has no bearing on his bat speed. That makes his presence on this list more confusing. We could say that he's slowing his bat down to prioritize contact, but he's also hitting more home runs in June than in May. Perhaps both can be true.

If you go further down the list, Ceddanne Rafaela is having the best month of his career, hitting .304, but he also has one home run in June after hitting five in May. His pull rate is up, but his fly ball rate is down significantly, so perhaps he's going to a more contact-oriented swing which has sapped some power but led to a higher average. Swings that are shorter to the ball can also register as "slower" given that the bat covers less ground to build up speed. That's why a contact-oriented hitter like Blake Perkins is on here despite having a slightly better month or Corbin Carroll shows up despite hitting .266 in June; however, Carroll's pull rate is down a lot in June while his flyball rate is up, so he's the opposite of Rafaela, which makes it hard to find a clear throughline with the names on this list. Maybe somebody smarter than me can help with that.

However, the truth of the matter is that a lot of these hitters are struggling.

Connor Joe has been one of the worst hitters in baseball in June, with a .123 average and just a 35 wRC+. His teammate Jack Suwinski has barely been better, Nelson Velazquez hit .122 and got demoted. Sal Frelick is hitting .254 but has just a .600 OPS and his teammate Rhys Hoskins is hitting just .197 in June with a .588 OPS. William Contreras is also having a tough month, hitting .224 with one home run and a .556 OPS (are the Brewers coming back down to earth a bit?) Jeremy Pena has been awful in June and Alex Verdugo is hitting .214 with a .585 OPS.

OK, I guess this is not a list you want to be one with a few random outliers like Soto, Rafaela, and Abrams.

If we acknowledge that this list may indicate declining performance then some other names near the top of the leaderboard to be worried about are: Josh Rojas, Jose Caballero, Max Kepler, Jackson Chourio, Carlos Correa, Colton Cowser, Andrew McCutchen, Luis Garcia, Jurickson Profar, and Teoscar Hernandez. Then again, Bobby Witt Jr. and Vladimir Guerrero Jr., appear on that leaderboard too, so we can't simply use it alone to identify potential strugglers.

Some hitters who are gaining bat speed that might be heating up are Taylor Ward, Tyler O'Neill, Eugenio Suarez, Nick Castellanos, Wyatt Langford, and Harrison Bader.

Squared Up Gainers

I decided to go one step further and look at the players who increased their Squared-up Rate the most from May to June. As a reminder, Squared-up Rate tells us "how much exit velocity did a hitter get as a share of how much exit velocity was possible based on swing speed and the speed of the pitch." For example, a swing that is 60% squared up tells us that the batter got 60% of the maximum possible exit velocity available to him based on the speed of the swing and pitch. As such, it makes some sense that players who are squaring the ball up more often are likely to see improved results as their batted ball quality improves.

We've seen that from many of the names on this list, like Isiah Kiner-Falefa, Corbin Carroll, Michael Busch, Brandon Nimmo, Joey Meneses, and Cedric Mullins. Yet, just like on the lists above, guys like Eddie Rosario, Jacob Young, and Jose Caballero have been struggling this month, so squaring up the ball more is not, alone, enough to indicate success.

Blast Rate Gainers

So what about Blast Rate? "A blast, in Statcast terms, is when a batter squares up a ball and does so with a minimum amount of bat speed," so the hitters above have seen the biggest increase in blasts per swing of all hitters in June.

We see some of the same names on here like Tyler O'Neill, Brandon Nimmo, Paul Goldschmidt, Cedric Mullins, and Michael Busch. They've all been having solid months. Fernando Tatis Jr. was also having a great month before being sidelined with an injury, and Elly De La Cruz is hitting the ball much better in June than he did in May. Gavin Lux is showing marginal improvements, but nothing to be that excited about, and Mauricio Dubon has not been much better in June at all. Yet, he's the only real outlier here who is seemingly getting WORSE results despite making more meaningful contact.

We should just point out that Nimmo has shown up on a few of these lists, and Scott Pianowski and I also discussed him as a trade target on our recent podcast. His early-season batted ball data looked good despite his struggles, and he's really been coming on of late.

Takeaways

At the end of the day, after going through all of these metrics on a month-by-month basis, I think it's clear that they can't be used to identify hot streaks or cold streaks alone. They all do a pretty solid job of highlighting hitters who are improving or declining, but they don't always tell us WHY, so there will be some exceptions.

In my opinion, the best way to use these stats is as an extra layer of research when looking into a player's struggles. Blast rate improvement seems to be the simplest to look up because, in many ways, it's kind of like seeing who has experienced the biggest improvement in barrel rate. We understand it as a concept, and we know it's mostly a positive development, and we should be intrigued by those hitters but some will not perform up to that barrel rate.

I also like the idea of using bat speed to crosscheck potential concerns about a player. For example, there were concerns early on about Paul Goldschmidt getting old, or Jesse Winker and his history of back injuries, or Nick Castellanos' second-half slide last year. If we see that those players are starting to produce more consistently and then can also see that their bat speed is increasing, we can assuage some of our concerns about aging or injury. Meanwhile, previously injured players like Rhys Hoskins starting to swing slower could be concerning, while early hot starters like Connor Joe, Jurickson Profar, and Jeremy Pena seeing a decrease in bat speed or squared-up rate could give us insight into just how real (or not) those hot streaks were.

At the end of the day, they may not be game-changing stats, but they're another tool in our tool belt that I think gets interesting as we can start comparing data month over month and year over year.