Stroman Sliding Back to the Front of the Rotation

Well well, this is a nifty leader board. Marcus Stroman and Aaron Sanchez, the two young Blue Jays, are best friends forever. After so many sleepless nights softly whispering “hashtag StroChez” into each others ears and watching Netflix together at their City Place condos, their pitching philosophies must be rubbing off on each other:


Earlier this week, I wrote about how much of J.A. Happ’s success this season can be attributed to Toronto’s stellar defence. Marco Estrada and his 47 percent fly ball rate missed the memo, but the rest of the Jays rotation is taking advantage of its Gold Glove infield; Marcus Stroman is leading the charge with an absurd 60% ground ball rate.

Ground ball pitchers are alive and well in 2016. Dallas Keuchel, Jake Westbrook, and Jaime Garcia all come to mind. But any conversation about groundballers has to turn back the clock and start with Derek Lowe.


Only Brandon Webb has a higher career average since 2000, but Lowe threw almost twice as many career pitches as Webb. He was a double play machine who got it done with a slow sinker that he rode to a 40.3 WARP over his 16-year career.

The Marcus Stroman that debuted in 2014 didn’t look much like Derek Lowe, and if you tried to make that comparison to his face he would probably subtweet a cry-laugh emoji at you. But in three short years, Stroman has already been through a career-threatening injury and the version that has emerged looks nothing like the original. He might still love inspirational quotes as much as the old one, but this new Stroman might also take a Derek Lowe comparison as a compliment.

Here’s the major difference between Stroman 1.0 and Stroman 2.0:

Brooksbaseball-Chart (2)

Bye bye four seam, hello sinker. It’s not hard to see, unless you’re having trouble distinguishing between black and dark grey. The switch resulted in a higher-than-Lowe 64 percent ground ball rate over a super small 2015 sample, but 2016 is proving that it was no fluke.

So the sinker is great. The sinker was Stroman’s ticket back to the mound during the playoffs last season, and it’s generating a ground ball 66 percent of the time when hitters make contact. But let me draw your attention back to the graph above. That red line that’s rising? That’s his slider, and this year it’s generating a ground ball 68 percent of the time (see table below). Only Jacob DeGrom’s slider (64 percent) comes close to that kind of ground ball generation.

The year-by-year view above makes it look like a subtle change, but if we zoom closer into 2016 it’s easier to see that Stroman is falling head over heels in love with his slider.

Brooksbaseball-Chart (1)

He’s still getting tons of ground balls on his sinker, but hitters are mashing the pitch to the tune of a .318 AVG and .468 SLG. Meanwhile, the slider has held opposing batters to a .183 average and a .278 slugging percentage. That’s understandably caused Stroman to back off the sinker and throw his slider more often than he ever has in his career over the past two months.

We don’t usually associate sliders with ground balls – the league average ground ball rate on sliders is 46.2 percent this year – but Stroman’s slider is not league average. According to Brooks Baseball, the -2.6 inches of vertical drop he gets on the pitch ranks behind only Jaime Garcia, Dallas Keuchel, and of course, Chris Sale. In fact, the league average vertical break on sliders this season is +1.6, and only six pitchers besides Stroman get more than an inch of drop on their slider. That kind of exceptional depth is rare, and makes it almost impossible for a hitter to get under the ball as it dive-bombs underneath the barrel of the bat.


Here’s a visual from his dominant start against Houston on August 1, in which nine of his 13 strikeouts came on the slider. Look at how he’s able to spot it consistently low in the zone even thought it looks like it’s coming in at the belt when he releases it.

Stroman’s season numbers don’t look too good right now, but since he started trusting his slider back in July, he’s pitched to an ERA of 3.24. More importantly, the strikeouts are back. He has fanned 9.5/9 over that span while walking only 1.2/9, which is a big reason why he leads all of baseball with a 2.48 xFIP since the All-Star break.

If I wanted to continue down the comparison road, I could point out that Lowe also gradually ramped up his slider usage in the early years of his career, eventually dumping his curveball and changeup almost entirely in a 2008 campaign in which he threw his slider 32 percent of the time and his sinker 61 percent of the time. According to WARP, throwing either a sinker or a slider 93 percent of the time resulted in by far the best season of Lowe’s career. He posted a 3.38 GB/FB ratio en route to a 3.24 ERA and a career-high 147 K’s for the first-place Dodgers.

When you get down to it, though, Stroman is incomparable. His fastball is classified as a sinker, but if you’ve ever seen the tantalizing horizontal movement with your own eyes, you know it’s not your daddy’s sinker. He also plays with the untethered exuberance of Russell Westbrook putting back his own free throw miss, and comfortably mixes in six different pitches like he’s a grizzled Greg Maddux.

Actually, according to PITCHf/x, Greg Maddux only had five pitches in his arsenal. Stroman is clearly his own man.

Lead Photo: Nick Turchiaro-USA TODAY Sports

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2 comments on “Stroman Sliding Back to the Front of the Rotation”


I really don’t get why he’s abandoned his four seamer. It seems like everything he throws is always down and away. I’m not a big leaguer or anything, but you’d think using the whole strike zone would be a good thing.

Elie Waitzer

I definitely see the potential in elevating his fastball once in a while later in the count. Right now he’s leaning very heavily on the down and away slider as his strikeout pitch which is working pretty well (9.7 K/9 since July) but might get predictable.

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