7/28/2021

Spin rate, up or down?

 

Spin rate has been discussed frequently since the statcast data available in 2015. This year, spin rate has been used as an indicator to check whether a pitcher possibly uses foreign substances. On June 21, MLB enforced the rule of prohibiting the use of foreign substances by pitchers. Since then, what really happened?




Before June 21, the Dodgers pitching staff threw 4-seamers with an average spin rate of 2548 rpm. After June 21, the average spin rate drops to 2356 rpm. That’s a nearly 200-rpm drop. But, the Dodgers are not the only team to see a drop in 4-seamer spin rate. Actually, all 30 MLB teams see a drop in average four-seamer spin rate.

Spin Rate Leader

(4-seamer, Min Pitches: 500)

Before 6/21

Player

Spin Rate (Avg.)

Trevor Bauer

2795

Walker Buehler

2610

Dylan Cease

2607

Garret Richards

2571

Mike Minor

2548

Gerrit Cole

2534

Julio Urias

2507

Max Scherzer

2481

Andrew Heaney

2480

Tyler Mahle

2435


Before June 21, the average spin rate of Trevor Bauer’s 4-seam fastball was 2795 rpm. He’s the only player to throw a 4-seamer at over 2700 rpm. Bauer’s four-seamer was quite effective and opponents batted only .154.


Walker Buehler’s four-seamer is dominant as well. Before June 21, batters only hit .187 against Buehler’s 4-seamer. The average spin rate of his four-seamer was 2610 rpm.

 

Dylan Cease’s four-seamer was spinning at an average rate of 2607 rpm before June 21 and his BAA was .244.


Garrett Richards also throws a high-spin four-seamer. His four-seamer had an average spin rate of 2571 rpm, but it wasn’t very effective. Batters have a batting average nearly .300 against Richards’ four-seamer.

 

Moreover, the average spin rate of Mike Minor’s four-seamer was 2548 rpm. Gerrit Cole and Julio Urias each threw four-seamers that frequently hit 2500 rpm before the rule was enforced.


So, since June 21, do we see huge changes in spin rate?

 

Spin Rate Leader

(4-seamer, Min Pitches: 250)

2021/06/21~2021/07/27

Player

Spin Rate (Avg.)

Julio Urias

2455

Andrew Heaney

2398

Jameson Taillon

2389

Dylan Cease

2383

Gerrit Cole

2356

Charlie Morton

2317

Carlos Rodon

2312

Vince Velasquez

2300

Nick Pivetta

2268

Kevin Gausman

2260


Since June 21, Julio Urais’ four-seamer has had an average spin rate of 2455 rpm. Urias has 12 wins so far, but his four-seamer isn’t very effective. Batting average against his four-seamer is over .300 so far this season.


The spin rate of Urias’ four-seamer dropped a little bit after MLB enforced the rule of prohibiting the use of foreign substances. But he’s not alone. Dylan Cease’s four-seamer spun at a rate over 2600 rpm before June 21. But his four-seamer spin rate drops to 2383 rpm and opponents hit very well with a batting average of .313. In addition, on average, Gerrit Cole’s four-seamer was at a spin rate of 2534 rpm. After the rule was enforced, Cole’s four-seamer spins less, with an average spin rate of below 2400 rpm. But a lower spin rate in four-seamer doesn’t create big problems for Cole, opponents hit just .207 against his four-seamer since June 21.


When we look at spin rate changes after MLB enforced the rule, we have seen that each team’s pitchers throw four-seamers with a lower spin rate. It’s unclear whether Trevor Bauer will be back this season, but he made two starts after the rule enforcement and tossed 12 innings. Average spin rate of his four-seam fastball was 2573 rpm in these two games. It’s been over a month since the MLB enforced the rule. The rule might change spin rate. But, it’s only a month after the rule was enforced. We still have two more months to see whether the trend will continue.

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