Matt Strahm’s Next Step Hinges On His Slider

Nearly 800 pitchers registered an out in MLB last season. If you happened to pick out one who threw 60+ innings in relief, and had more than a strikeout an inning, you’d probably say that pitcher had a pretty good year. His team would have been happy to have him provide those innings.

That was Matt Strahm last year for the Padres. After acquiring him from the Royals in July of 2017, he provided San Diego with a lefty arm out of the bullpen who could bring a mid 90s fastball, an elite slider, a surprising changeup, and a show-me curveball.

Strahm came from relative obscurity. He was only a Royal after the team won the World Series and was clearly not the same caliber. He also clearly had control problems, and tore the patellar tendon in his left knee just weeks before the Padres traded for him.

But San Diego let him get healthy, and he was a quality get for them. Now they’re looking to leverage his talents even more by making him a starter as the team eyes contention.

Except that could be hard with the current version of Strahm. The Padres executed a deliberate and cautious plan for him in 2018. He pitched only seven times in the same series all year. He also only pitched on back-to-back days twice, each time after having rested for at least the previous four days. And when you’re a pitcher deployed that way, you hardly ever get the chance to see the same lineup twice, let alone three times, as a starter could. And so you can simply approach each at-bat differently.

Strahm’s pitch mix tells us as much.


There’s a lot to consider here. First and foremost is that Strahm has a starter’s repertoire, both by volume and distribution. Having more up his sleeve ultimately makes him less predictable to hitters at any given moment. That’s a good thing. But there are some caveats.

One is that of his four offerings, there’s only enough of a sample size of his fastball and changeup to consider his whiff rates stable. Given how crucial strikeouts are to success for today’s pitchers, we can’t just write that off. As much as we can project with publicly available information what Strahm might do as a starter based on what he did in relief, we’re probably committing equally to a hypothetical outcome at best.

If we look at how he approached right- and left-handed hitters separately, those sample sizes get even smaller. We also see almost  two different pitchers. This is normal. Even Max Scherzer has a different approach to different-handed hitters.

The biggest difference in Strahm’s varied approaches and pitch effectiveness in 2018 lay in his breaking balls. To lefties, he primarily used his slider slider down and in. Overall, it generated nearly nine percent more whiffs than league average. The thing is nasty.

But to righties, Strahm favored his curveball to the same part of the zone. Overall, it generated four times fewer whiffs than league average.

That may be due to how he used it: the pitch led his third-most frequent pitch pairing to righties, and he often followed  it up with a fastball high and away. That could’ve helped his fastball play up — imagine trying to hit a dart at 95 mph after a dipper at 78 — but it is a bit backwards. Curveballs aren’t often a setup pitch.

Matt Strahm’s breaking balls

This gif shows where Strahm threw each of his breaking balls to right- and left-handed hitters in 2018. In parenthesis is the amount of times he threw that pitch in that context. He distributed the different pitches relatively equally to similar parts of the zone.

It also gives us an idea how that same slider that was so dominant against lefties wasn’t nearly as useful against righties, who took it for a ball nearly 50% of the time they saw it. Maybe it was something in how he was trying to locate it, or maybe it became harder to locate when going back and forth between that and his curveball.

Regardless, right-handed hitters were definitely seeing his best pitch differently than left-handers. It’s understandable why he’d willing to lean on primarily the curveball to righties, then, if it allowed him to at least establish a cadence against them. But when it’s a pitch that isn’t in a spot where guys are willing to swing, and isn’t good enough to coax swings in spite of that, why not seek to maximize the elite slider you already have?

There could be a blueprint for how Strahm could do it. Patrick Corbin became a top-five pitcher in MLB last year by manipulating his slider in such a way that allowed him to work both sides of the plate to any hitter. He takes a slower slider and drops it arm-side to steal strikes and get chases, and then frisbies a harder slider more to his glove side to evoke hapless whiffs. He finished 2018 with a slider whiff rate north of 30% and a heatmap that looks like this:

Patrick Corbin’s crazy slider(s)

Corbin also transitioned from throwing his slider just under 40% of the time to throwing it nearly 50% of the time, and he did it almost exclusively by dropping his worst pitch, his changeup. You can read all about his unique breakout across the internet.

The thing about Corbin manipulating his slider to create two pitches from it is that classification systems have differentiated his slow slider as a curveball. And Matt Strahm already throws a curveball with a similar velocity gap to his slider as between the two for Corbin. And Corbin’s worst pitch was his changeup, and Strahm’s changeup flashed above average last year in his first full season.

So it’s not that Corbin is an exact blueprint for Strahm. Rather, he’s a recent, left-handed example of how use your best stuff to control the zone.

Controlling both sides of the plate with a pitch is hard. It may be especially challenging for Strahm to do with his slider, since it’s a pitch that breaks differently to different sides of the plate

But if Matt Strahm is going to be a quality starting pitcher, it could hinge on the evolution of his slider. San Diego has the time to afford him to figure it out. It’s just a matter of if they’ll take it.

Pitch mix data and heat maps from Baseball Savant. League average whiff rates from research by Alex Chamberlain. Pitch pairing data from Baseball Prospectus. Feature image from Jeff Haynes/AP. 


One thought on “Matt Strahm’s Next Step Hinges On His Slider

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s