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Luke Weaver's Next Step to Stardom

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A reliable third pitch could make or break the righty's future as a frontline starter

MLB: Pittsburgh Pirates at St. Louis Cardinals

Some phenomenons just can't be explained: people spending actual money on selfie sticks, what historians will inevitably refer to as the Great Romphim Crisis of 2017, and these St. Louis Cardinals somehow sitting just two games back of the division lead. Three of the club's five primary starters this season have posted xFIP-'s of 100 (league average) or worse. In spite of this fact, St. Louis has been buoyed by a plethora of midseason callups, including Tommy Pham, Paul DeJong, Magneuris Sierra, Harrison Bader, John Brebbia, Luke Voit, and the subject of today's article: Luke Weaver.

Granted, Weaver's first cup of big league coffee in 2016 appeared much worse on the surface than in reality, in large part due to a BABIP and LOB% of .386 and 61.8%, respectively. But he by no means looked like the stud we have seen of late.

Matthew Ludwig wrote about Weaver last week and how his changeup in tandem with his fastball have formed a devastating one-two punch. I completely agree with Matthew's assessment of the changeup in a vacuum, but the feasibility of a standout big league starter throwing only two reliable pitches has to be questioned.

Per Brooks Baseball, Weaver threw the cutter 7.92% of the time last season; the curveball 6.89%. Admittedly, I was rather impressed by what I saw from Weaver's cutter last year. That said, it appears that he has chosen the curveball as his go-to third pitch, with its usage rate since August 2nd (the eight strikeout performance in Milwaukee that kickstarted his current run) of 10.59% dwarfing the cutter's microscopic 1.62%.

Luke Weaver Curveball and Cutter Results

Pitch wOBA xwOBA Whiff/Swing% GB% LD%
Pitch wOBA xwOBA Whiff/Swing% GB% LD%
August 2nd and After Curve 0.300 0.218 26.3% 72.7% 9.1%
2016 Curve 0.358 0.500 6.7% 27.3% 45.5%
2016 Cutter 0.591 0.364 28.0% 20.0% 40.0%

This year's curveball has enjoyed a level of success unlike any prior third pitch. Is it any surprise that Weaver's xFIP rose from 1.72 to 4.59 the second time through the order last season compared to just a 15 point jump (2.03 to 2.18) since August 2nd?

Don't get me wrong, the curveball in its current state has a long way to go. One of the pitch's main critiques is that it lacks the sharp 12-6 drop that we have been treated to from Cardinals greats like Chris Carpenter and Adam Wainwright. However, a curveball with more slider-esk movement can still be an effective pitch. Just ask a pitcher superior to Weaver in both pedigree and hair: Jacob deGrom. Both throw a faster curveball located away to both righties and lefties alike, with the focus on horizontal movement rather than pure vertical drop. Skeptics were unsure of deGrom's curve as well. Here's what Jeffrey Paternostro of Amazin' Avenue–while we're on the subject of curveballs, Adam Wainwright says hi to any potential Mets fans reading–said about the future Rookie of the Year back in 2013.

“I don't know if the secondaries are good enough for him to start. The potential of the fastball to play up in shorter outings makes him an intriguing option out of the major league pen…Can the curve develop into a legitimate major league offering?”

Spoiler alert: it did develop. In the three seasons of available Statcast data, deGrom's curveball sports a .299 wOBA with an xwOBA not too far behind at .314. Take a look at how he fans Nick Williams with a curveball away following an inside slider and an up-and-away fastball to set up the 2-2 count.

This is the power of pitch sequencing with an arsenal that includes legitimate secondary pitches.

The same principle also applies to Weaver, his September 8th outing against the Pirates included. After seeing three consecutive fastballs before a changeup that led to a double play in his first at-bat, Jordy Mercer was not expecting Weaver to break out a first-pitch curveball in round two.

I can't stress enough that Weaver's curveball is still a work in progress. Every now and then the pitch still catches the heart of the plate, much like this hanger that resulted in an Elias Diaz base hit.

It's easy to lose sight of the fact that Weaver is a 24-year-old who has accumulated all of 78 MLB innings. But this is a former first round draft pick with first round talent. He's a student of the game who has already begun tinkering with the curveball after working on the pitch with a great mentor in Adam Wainwright.

“The curve is a pitch I’m transitioning, I’m trying to use it in more aggressive ways,” Weaver said. “At first I was just trying to steal some strikes and get ahead, get it over the plate. Now I’m working that into how can I make this into a strikeout pitch. So I’m talking to Wainwright about what he’s doing in certain counts to make that an effective pitch.”

Weaver's apprenticeship under Wainwright will presumably lead to a slower curveball with bigger break. As much as it may sound like I'm an adamant supporter of the deGrom-styled curveball, I would absolutely welcome Weaver into camp next year–a rotation spot seemingly secured–with the plan that he would experiment with various types of breaking balls.

The future is now in St. Louis. And just in case you forget, every fifth day on a mound in Busch Stadium or elsewhere, the lights will rain down on one subject, and one subject only.

The kid from Florida State will be there to remind you.