Pittsburgh Pirates: Spin Rates Powered Chris Stratton’s Breakout Season


While on the surface Chris Stratton’s breakout might seem like a surprise, the spin rates make it clear he’s always had the potential to be a great pitcher for the Pittsburgh Pirates

If you were to analyze Chris Stratton based on the surface numbers, you’d probably think that Stratton’s breakout campaign with the Pittsburgh Pirates in 2020 is a big surprise. Sure, he was drafted in the 1st round, but from 2016 to 2018, he had a 4.63 ERA, 4.36 FIP and 1.45 WHIP.

Last year, Stratton started off the 2019 season with the Los Angeles Angels, and pitched just 29.1 innings. In that short amount of work, he allowed six home runs, walked 18 batters, only struck out 22, and gave up 28 runs. He was designated for assignment by the Angles when he was picked up by the Pittsburgh Pirates.

Stratton showed some promise, but still put up underwhelming numbers with a 3.66 ERA, 4.11 FIP and 1.39 WHIP in 46.2 innings. He did see his walks go down with a 7.5% walk rate and his strikeouts go up with a solid 23.5% strikeout rate, but he had a HR/9 of 1.4.

Through the first few years of Stratton’s career, he only had a 4.88 ERA, 4.51 FIP and 1.50 WHIP in 289.2 innings. Stratton had a sub-par strikeout rate of just 18.8% and an average at best walk rate of 9.5% in these first four seasons. His ERA estimators weren’t all that great either with a 4.78 SIERA and 4.57 xFIP.

But in 2020, Stratton was really good with the Pittsburgh Pirates. In 30 innings, the right hander has a 3.90 ERA, 3.18 FIP and 1.30 WHIP. While he does have an uninspiring ERA, remember to always take a grain of salt when looking at relief pitcher ERA, even more so in a 60 game season. Entering Friday, it was 3.16 before he made the gracious sacrifice to give up three runs to the Indians to help the Pirates get the first-overall pick in 2021’s draft.

He still isn’t a control artist of any sort with a 9.8% walk rate, but he’s seen his strikeouts rise dramatically to 29.8%. His home runs also have been allowing less home runs with a 0.9 HR/9. All of his ERA estimators seem to be in agreement that he isn’t getting terribly lucky either with a 3.48 xFIP, 3.42 DRA and 3.49 SIERA.

Now his numbers based on years prior, and what they are now might make you believe that this is surprising. How does he go from a mediocre swing-man to a very effective relief pitcher? Well you have to look at the finer details in Stratton’s game, more specifically his spin rate.

But first, what is spin rate? Why is it important? It’s the amount of rotations per minute a pitcher places on their pitches. A four-seam fastball naturally has backspin when thrown. You may have heard about rising fastballs, and while it is physically impossible to do in a baseball game as you would need to throw a fastball at 113 MPH with at least 3100 RPM to create any actual, physical rise, the spin causes the ball to have a rising appearance, and you don’t necessarily have to throw hard to get that rising effect. Batters know what a 93 MPH fastball looks like, and where it should end up. How gravity will affect its travel. But if you put enough spin on it, the ball doesn’t fall as fast as it has less upward moving air, creating a rising optical illusion.

Stratton only averages 93.2 MPH on his fastball, which sits in the 54th percentile. But the amount of spin he puts on it is extremely impressive. With 2627 RPM, the pitch doesn’t fall nearly as fast as one that sits around average in terms of spin rate (around 2250 RPM). His fastball spin rate is the 7th highest in all of baseball. The spin rate on his fastball is getting a lot more swings and misses.

As fellow Rum Bunter writer Steven Strosko pointed out last week, Stratton has a fantastic whiff rate. At the time when he wrote his article, Stratton had a 39% whiff rate, and while it has gone down since, he’s still sitting with an outstanding 35.3% mark. Though he is getting fewer swings and misses on his breaking pitches, the spin rate seems to be working really well for his ‘rising’ fastball, as batters have swung and missed at it 39.1% of the time compared to just 29.4% in 2019.

His fastball isn’t the only pitch he has insane spin on. Stratton’s slider has 2880 RPM, and his curveball sits in the top 97th percentile of spin rate as well with over 3000 RPM (3088). He ranks as the 6th high curve spin rate, meaning they could also be extremely effective pitches.

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Stratton has seemed to have mastered his fastball. He’s getting way more swings and misses on it, and he could get better. While he has gotten his fastball on track, it’s very possible he gets one of his breaking pitches on track too. They might not be awful pitches, but he has room to grow, and I think he could get better.