Photo by Frank Jansky/Icon Sportswire

In the three years that Michael Fulmer has been playing in the major leagues, he’s proven to be a solid pitcher, ending 2016 with a 3.06 ERA and 2017 with a 3.83 ERA, both looking fairly legit when you check out the peripherals around them.

The one thing Fulmer’s been lacking has been strikeouts, but that might change with a switch he’s made in his repertoire and his pitch mix. Last Thursday, Fulmer was able to take down the Pittsburgh Pirates to the tune of six innings, zero earned runs, and nine strikeouts. He’s only had nine or more strikeouts three other times in his career and only once last year.

It was a great outing, and it had me wondering if the changes Fulmer has made this year could lead him to see more strikeouts. He’s totally changed his slider as a pitch and mixed around his pitch repertoire a bit.

Speaking of which, let’s take a look at his pitch repertoire.

First, we’re going to start with the two potential problems in Fulmer’s repertoire. Here, we have his sinker:

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It’s a good pitch, but it’s a groundball pitch and not really a strikeout pitch. It comes in around 95 MPH on average with decent movement on it, but so far this year, it’s been one of the weakest pitches Fulmer throws.

Last year it generated a solid 52% groundball rate and opposing hitters had just a .067 ISO and .278 wOBA against it. This year, though, his sinker is generating a 40.9% groundball rate and opposing hitters have a .192 ISO and .418 wOBA against it. If Fulmer’s going to see sustained success, he’s going to need to improve his sinker. Some of that will happen on its own, the pitch also has a .386 BABIP against it which won’t stay all year, but some of it will require increased control of the pitch. Last year he threw the pitch in the zone 59.1% of the time, this year that rate has dropped slightly to 55%.

Fulmer also has a changeup:

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It’s got some good, above-average horizontal movement to it, which is why it’s got a solid 13.5% whiff rate and 41.9% chase rate on the year. This is similar to last year, when the pitch had a 17.3% whiff rate and 41.7% chase rate — if this pitch is good at anything, it’s missing bats.

Problem is, Fulmer is prone to making mistakes with it, which is why opposing hitters have a .421 wOBA and a .235 ISO against the pitch so far this year. That’s a fair bit worse than last year, when opposing hitters had a .278 wOBA and .165 ISO against the pitch. It’s not abundantly clear why the numbers on his changeup are so much worse this year, but I do have one theory.

The only difference between this year’s changeup and last year’s changeup is movement — and not horizontal but vertical. Fulmer lost about two inches of drop on the pitch, and I think that’s why the contact rate on the pitch has jumped up from 67.4% last year to 76.7% this year. He’s still controlling it the same and locating it the same, it’s just lost some movement, and I think that’s made it slightly more hittable.

Now you’re all like “Okay Ben, cool, so I’m a lot less confident in Fulmer now than I was before, is this what you wanted?” The answer to that is no, it’s not, but I don’t want to be one of those analysts who cherrypicks stats to fit whatever narrative I want. There are improvements that Fulmer needs to make, if there weren’t, he’d basically be Clayton Kershaw, and he isn’t.

But he has made some interesting changes that could mean good things in the future.

First off, he’s using his curveball a lot more:

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Fulmer added this pitch to his repertoire last year, but he barely threw it. In 164.2 innings pitched last year, Fulmer threw the pitch a whopping 12 times. That was good for about 0.5% of the time. So far this year, he’s thrown the pitch 36 times, right about 8% of the time now, and the results have been very positive.

So far, the pitch has generated a 16.7% whiff rate, the second-best of all his pitches. He’s also locating it exceptionally well, throwing it in the zone 69.4% of the time so far. When hitters do make contact with the pitch, they aren’t hitting it very hard, with a .178 wOBA against the pitch so far.

As far as movement goes, it’s a lot closer to a knuckle curveball than your traditional curve, with relatively average movement, but above-average velocity, coming in at about 85 MPH on average.

Then, there’s his new slider:

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It’s a nice pitch and, so far, it’s been his best strikeout pitch, generating an 18.3% whiff rate and a 39.1% strikeout rate. That’s a pretty noticeable improvement over last year, when the pitch had a 14.1% whiff rate and a 25.2% strikeout rate, and it’s all thanks to the fact that he’s change the pitch.

Last year, Fulmer was throwing a slider that was all about vertical drop and not really about horizontal movement, which you can see here:

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This year it’s the reverse — the pitch is all about horizontal movement with not much vertical movement to speak of:

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As a result, it’s a better pitch, with about two inches more horizontal movement on it than your typical slider. That’s what’s made it so hard to hit and why opposing hitters have just a .183 wOBA against it.

He’s also controlling it a lot better, throwing it in the zone 51.6% of the time this year. That number was just 41.4% last season.

So what can you take away from this about Michael Fulmer? He’s got a new slider that he’s controlling well and is turning into the best strikeout pitch he’s ever had, and he’s utilizing his new curveball from last year more than ever before and it’s been effective. If he can wrangle in his changeup and sinker and turn them into more effective pitches (or even just slightly effective), Fulmer could be in for a very good season. Either way, we could be seeing his strikeouts go up.