St. Louis Cardinals: What does spin rate tell us about Matt Bowman?

Charles LeClaire-USA TODAY Sports
Charles LeClaire-USA TODAY Sports /

Matt Bowman had a strong rookie season for the St. Louis Cardinals after joining the club via the Rule 5 draft. What was his key to success, and can he repeat his performance in 2017?

When the St. Louis Cardinals selected Matt Bowman in the Rule 5 draft before the 2016 season, it wasn’t clear how he’d fit with the MLB club. Derrick Goold reported then that GM John Mozeliak suggested Bowman would have a chance to win a long relief role.

Bowman struggled at AAA in 2015, so the idea that he could become an impact arm for the St. Louis Cardinals bullpen seemed far-fetched. Yet, he accumulated 67.2 innings, more than any Cardinals reliever not named Seung-hwan Oh. Additionally, with a 3.46 ERA, he solidified himself as one of the team’s more reliable relief options.

As Seth Maness struggled through injuries and ineffectiveness, Bowman took over the “Seth Maness” role. As I define it, the “Seth Maness” reliever is a groundball pitcher who gives the team a chance to escape jams with one double-play-inducing pitch.

He’s a living, breathing fire extinguisher. Bowman induced grounders on 61.7% of batted balls, better than Maness career rate and tenth-best of 135 qualified relievers last year.

Thanks to that groundball tendency, Bowman limited the quality of contact against him. To quantify this, I ran Bowman’s batted balls through the xSTAT models I introduced here. Based on that analysis, Bowman’s success was not a fluke – his .270 BABIP and HR/FB rate were about what we’d expect based on the exit velocity and launch angles against him.

So why was Bowman so good? The answer might be spin rate, or, rather, a lack thereof.

Two years ago over on Baseball Prospectus, Alan Nathan detailed the importance of spin rate and useful spin. I’m oversimplifying here, but for pitches thrown with backspin (fastballs and changeups), more spin results in more rise and less spin results in more drop.

It would make sense, then, that a groundball pitcher should seek to minimize the spin rate on his fastballs and changeups. If he can do that, his pitches would drop more than the batter expected and he should induce more groundballs.

This is exactly what Bowman did in 2016. His fourseamer spin rate ranked 28th-lowest among 495 pitchers who threw at least one hundred fourseamers. Bowman’s average FF spin rate came in at 2043 RPM, about 1.6 standard deviations below the mean of 2256.

His twoseamer exhibited similar characteristics. The average spin rate on his FT was 1969 RPM, while the league average was 2166. Again, he was about 1.5 standard deviations below the mean.

His changeup took this tendency to the extreme. The average spin rate on his changeups was only 1103 RPM, about 600 RPM and 2.5 standard deviations below the league average. Consequently, his change had the 19th most drop as measured by zMov among the 289 pitchers with at least 50 IP.

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Spin rate for a given pitcher tends to be very consistent year to year. Therefore, it is unlikely that Bowman’s spin rate will change much next year, a positive indication that he’ll continue to show an elite ability to induce grounders. If all goes as planned, Bowman will again assume the fire extinguisher role for the St. Louis Cardinals bullpen in 2017.