MLB's crackdown on foreign substance use by pitchers is now a week old. The memo announcing that change was coming is a little over three weeks old. We're still only just seeing the early effects of what this will mean for baseball but we also don't necessarily have the luxury of waiting around for robust data sets when we're chasing Fantasy championships. If this is going to wreck your aces, you need to know now -- even though you can't possibly know right now. But, we can at least look into the numbers to see what the early trends suggest. 

I took a look at league-wide trends in another column, so now we're going to take a look at some individual trends that are popping up. There are some obvious high-profile pitchers who seem to have been impacted, but it's not entirely fair to just pick those high-profile examples and focus on them only. So, first, let's see which pitchers have seen the highest drop in average spin rate on their four-seam fastballs from the first two months of the season to the post-memo period -- the post-crackdown period only covers one week, or just one start for nearly all pitchers, which isn't enough data to draw many conclusions. 

Not that three or four starts is necessarily enough to draw concrete conclusions, but it's more than one, at least. We'll want to continue to keep an eye on this, but here's what that data shows so far: 

Biggest spin rate losers


Spin Rate change

% Change

Bauer Units % change

Trevor Bauer




Tyler Anderson




Griffin Canning




Gerrit Cole




Dylan Bundy




Walker Buehler




Tyler Mahle




Kris Bubic




Wil Crowe




Taijuan Walker




("Bauer Units" is a metric from DriveLine baseball that highlights the relationship that fastball velocity and spin rate share -- generally speaking, spin rate rises as fastball velocity does. So, Bauer Units is an attempt to normalize spin rates based on velocity. Bauer is actually throwing slightly harder than he did before the drop in spin rate, making the change look even more pronounced by this measure.)

If you've been following this story, there shouldn't be much surprise that Bauer tops the list. He was arguably the first person to really bring to light the impact foreign substances can have on spin rate, and he had one of the most dramatic increases in spin rate we've seen from 2019 to 2020. It probably isn't particularly surprising that Cole is near the top, either -- he's almost certainly who Bauer was obliquely referring to when he basically accused the Astros of systematically using foreign substances a few years ago.

There are some other interesting names here, including 2021 breakouts Mahle and Walker. But there's also Bundy, one of the bigger disappointments in the league, as well as Buehler, who has pitched well but also had the lowest strikeout rate of his career even before the crackdown began. 

Bauer and Cole are by far the most interesting names here, because there does seem to be a straight line between their recent struggles and the increased attention to what pitchers may or may not be putting on their fingers when they throw. 

Bauer made his first start in June on the sixth, and while it's not like he's been bad, he's looked a bit more like the frustratingly inconsistent version of himself we got to know before 2020. He had one brilliant start -- 8 strikeouts, 0 ER in 7 IP vs. ARI on June 18 -- and a couple of decent starts, and it all adds up to a 3.55 ERA in 25.1 IP since the start of the month. The strikeouts have still been there, but Bauer has regressed in one key way -- control. 

And that's a concern. Bauer is at an 11.7% walk rate over his last four starts, with at least three in three of the four. He had more than two walks in just three of his first 12 starts, while sporting a 7.8% walk rate in that span. The rate from his first 12 wasn't quite as good as his career-best 2020, but it was certainly a lot better than his recent stretch, which would be the worst of any full season in his career if he sustained it. 

Bauer could get away with giving up too many fly balls and home runs in 2020 and his first two months of 2021 because he was racking up huge strikeout numbers and mostly limiting the homers to solo shots. However, when he's really struggled in his career, it's been because too many of the home runs were coming with runners on base. If his control continues to lag behind, it could be a return to the days when Bauer was maddeningly inconsistent. 

Bauer can at least take heart in knowing that things have been even worse for his former college teammate and constant rival, Cole. Cole has made five starts since the release of the memo, and he's got an ugly 4.65 ERA in that stretch. 

Control hasn't been an issue so much for Cole (6.3% walk rate), but everything else has seemingly gone sideways. Cole has a 25.4% strikeout rate, a downright pedestrian mark for a guy who has been at or above 32.6% every season since 2018. He's also been hit very hard in this stretch, giving up nine homers in the five starts. And, as the home run he gave up to Rafael Devers on Sunday -- one of three he allowed on the day -- highlights, Cole's command has been an issue: 

How much of either pitchers' struggles (or any other pitcher's?) can be attributed to the crackdown? That's impossible to say for sure. For as much as we can measure these days, drawing a causal relationship between the change in the spin rate of Bauer or Cole and their results in a four- or five-start span is beyond our capabilities. 

That's one reason why this whole thing is so frustrating for Fantasy players and analysts alike: It introduces one more unknown element in a season that has been full of them. From the change in the composition of the baseball to the seemingly unprecedented pace of injuries we've seen, we're in the midst of a season that has been defined by uncertainty more than any I can recall. 

What I can say is along those lines is, the pitchers who have seen a dramatic drop in spin rate can probably be discounted for that simple reason: Unpredictability is bad for Fantasy. It's entirely possible this is just a random bump in the road for Bauer or Cole. Performance fluctuates for every player, and in sample sizes this small, we could just chalk it up to a cold streak or random variance.

However, we know spin rate does matter, and generating less of it does tend to make pitches perform worse. In the case of Bauer and Cole, both have filthy stuff even without the benefit of whatever they might have been using. And both can still dominate moving forward, too. But you have to be at least a little less certain about that for the rest of the season than you otherwise might have been.

It makes the margin for error slimmer. The more movement and deception a pitch has, the more likely you are to get away with your mistakes. A 99-mph fastball thrown belt high with a bit more spin might end up just above the barrel of the hitter's bat, leading to a lazy fly; if that pitch doesn't fool the hitter quite as much … well, you saw what Devers did to that pitch. 

Cole and Bauer don't have great command -- per Eno Sarris' Command+ metric at The Athletic, Bauer has the worst command of any pitcher in his top-25 rankings while Cole rates out as just slightly better than average -- so it's possible they may be more affected by any loss in effectiveness than most pitchers. That's my hypothesis, at least. It's not enough to change how I feel about either too much, but it does make Bauer more like a top-12 starter rather than a top-five one, while Cole may fall back to the pack compared to Jacob deGrom, who he has been battling with for the top spot in my rankings since the preseason. 

None of this is to say you should panic-trade either Cole or Bauer. Maybe it's just a bad few weeks at a weird time. Maybe they need to adjust. I still expect both to be very good -- and I'm similarly not drastically changing my view of any of the other big spin rate fallers. I'm just a little bit less sure of just how dominant they'll be moving forward. It's that uncertainty that hurts.