Well, Did the Mariners Cheat?

Spin rate and sticky substances, folks; they’re all the rage these days. With the crackdown on foreign substances beginning this week, pitchers will have to ditch the spider tack and sunscreen, pitching instead on good vibes and good vibes alone. If you’re a follower of the sabermetric section of baseball Twitter you’ve probably seen a few posts about stars like Trevor Bauer and Gerrit Cole’s regression in spin rates in recent starts, alluding to their statuses as members of the guilty party. 

Now you may be wondering: which side of the aisle does the pitching staff of our beloved Mariners fall on? Is a portion of Justus Sheffield’s start day routine devoted to applying spin rate enhancers to his glove that take a bachelor’s in chemistry to create? Or do Marco Gonzales and the rest of the crew pitch clean as a whistle, voiding the potential competitive advantages afforded to others in order to retain a clean conscience? Or is it somewhere in the middle, as pitchers have stated that substances can be used solely to get a better grip on the ball, not more rotation. 

I put together a less than perfect chart that details the percentage change of RPMs (rotations per minute) in individual pitch types from Mariners starting pitchers that sheds some light on a potential answer for that question. The methodology behind the numbers is rather simple, three start averages of RPM from before June 3, and three start averages from after that date are compared, with a percentage increase/decrease in spin rate available to interpret however you please. The date this graph is centered around is specifically June 3, as that’s the first date media speculation arose of a potential memo from the league office that may have been circulated to teams, leading to pitchers potentially fearing fines or suspensions. There’s one notable exemption from this list though; Justin Dunn does not appear on it because both spin rates and the eye test make it pretty clear he was fighting through injury in his two most recent starts, affecting the viability of his RPM numbers. 

        4 Seam Fastball    
    Before Memo   After Memo   Percent Change
Marco Gonzales   2,185 RPMS   2,229 RPMS   2.0% Increase
Yusei Kikuchi   2,245 RPMS   2,296 RPMS   2.3% Increase
Justus Sheffield    2,051 RPMS   2,042 RPMS   0.4% Decrease
Logan Gilbert   2,138 RPMS   2,122 RPMS   0.7% Decrease
Chris Flexen   2,119 RPMS   2,081 RPMS   1.8% Decrease
    Before Memo   After Memo   Percent Change
Marco Gonzales   2,189 RPMS   2,180 RPMS   0.4% Decrease
Yusei Kikuchi   1,697 RPMS   1,623 RPMS   4.3% Decrease
Justus Sheffield    1,825 RPMS   1,699 RPMS   6.9% Decrease
Logan Gilbert   1,390 RPMS   1,512 RPMS   8.8% Increase
Chris Flexen   1,323 RPMS   1,349 RPMS   2% Increase
    Before Memo   After Memo   Percent Change
Marco Gonzales   2,209 RPMS   2,175 RPMS   1.5% Decrease
Yusei Kikuchi   2,346 RPMS   2,336 RPMS   0.4% Decrease
Justus Sheffield    2,071 RPMS   2,052 RPMS   0.9% Decrease
Logan Gilbert   NA   NA   NA
Chris Flexen   2,271 RPMS   2,268 RPMS   0.1% Decrease
  Before Memo   After Memo   Percent Change
Marco Gonzales 2,356 RPMS   2,281 RPMS   3.1% Decrease
Yusei Kikuchi 2,402 RPMS   2,438 RPMS   1.5% Increase
Justus Sheffield  2,615 RPMS   2,583 RPMS   1.2% Decrease
Logan Gilbert 2,333 RPMS   2,274 RPMS   2.5% Decrease
Chris Flexen 2,675 RPMS   2,718 RPMS   1.6% Increase

After looking at the data, nothing jumps out as very evident proof of cheating. Sheffield is the only pitcher who decreased in all four pitch categories, and if I had to point my finger at someone I’d say has the highest likelihood of guilt, it would be him. The most noticeable percentage change in all of this is Logan Gilbert’s changeup; however, the positive spin rate increase as opposed to negative leads belief more towards a change in mechanics, or perhaps even just a change in mentality regarding the pitch as he gets more experience in the majors under his belt. With the exception of Sheffield, each pitcher is in the red in some categories, and in the green in at least one. The numbers certainly seem to show an average minor decrease across the board, but a percentage change within 2% feels insignificant in the grand scheme of things, as while pitchers like Gerrit Cole record spin rates the lowest they have on record since 2017, Mariners pitchers’ rates seem to follow the natural ebb and flow of a full season. 

If Mariners pitchers are using foreign substances, I genuinely believe that it’s done to improve grip, which I don’t feel is an irredeemable sin, nor something that evokes the word “cheater” in my head the likes of which trash can banging may. Frankly, if I was in the box facing someone throwing a baseball 95+ MPH near my head, for my safety I would hope they had all the substances necessary to grip the baseball to its fullest extent. That’s just how I feel though, and I would love to hear others’ reactions to these numbers.

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