This year, the Tigers' Matthew Boyd is throwing his slider more than twice as frequently as he did as a rookie in 2015. (Logan Riely/Getty Images)

One day in April 2012, Oregon State’s Matthew Boyd was playing catch with his pitching coach when, out of some combination of boredom and curiosity, he asked a fateful question: “How do you throw a slider?” One quick lesson on proper grip and mechanics later, Boyd, a then-21-year-old left-handed reliever with a fastball/curveball/change-up arsenal, unleashed the first slider of his life, a devilish missile with a sharp left-to-right break.

“I was like, ‘Oh, my gosh,’ ” Boyd, now the Detroit Tigers’ ace and one of the top starting pitchers in the American League, recalled recently. “That day, I messed around with it in the game, and I got a three-pitch strikeout to a lefty hitter. That’s how it all started.”

It is only a slight exaggeration to say the story of Boyd’s slider, from its humble origins to its standing as one of the game’s best, is the story of baseball in 2019. Boyd’s trademark pitch emerged from constant experimentation and refinement — honed by a heavy immersion in technology and data analytics at Driveline Baseball, a biomechanics lab/training facility outside Seattle that has become an industry leader in “pitch design” — and has become lethal to opposing hitters.

“You take the verbal cues I already had from coaches,” said Boyd, 28, “and take the high-speed camera showing how to grip and release it and the data showing what it’s doing, and it’s like: ‘Oh, man. Now I have a clear direction. Let’s go crazy.’ And it just got better and better and better.”

How is this the story of baseball in 2019? While fastball velocity gets more attention — and is responsible for much of the all-or-nothing, power-on-power approach to both pitching and hitting that defines today’s game — this season is more accurately defined as the Year of the Slider. If increasing fastball velocity is changing the sport, then the rise in the frequency and effectiveness of the slider is its chief accomplice.

This season has seen more sliders thrown, as a percentage of overall pitches — 18.4 percent, up from 16.9 in 2018 — than in any major league season since FanGraphs began tracking data in 2002. And slider velocity has risen — from 80.4 mph in 2002 to 84.5 this season — roughly in tandem with fastball velocity (up from 89.0 to 93.0 mph in the same span).

It stands to reason: Higher velocity leads to higher spin rates, and more spin means bigger breaks. According to data compiled by FiveThirtyEight.com, the average major league slider had about one extra inch each of horizontal and vertical break than it did in 2008.

The story of Boyd’s slider, then, is a microcosm of the transformation seen across baseball. It has lifted a seemingly ordinary pitcher — Boyd was never considered a top prospect and was 22-35 with a 5.07 ERA in the majors entering 2019 — to the cusp of all-star status.

This year, Boyd (5-4, 3.01 ERA) is throwing his slider more than twice as frequently (35.8 percent of all pitches) as he did as a rookie in 2015 (16.9 percent) — mostly at the expense of his sinker and curveball, both of which once featured prominently in his arsenal but which he has largely abandoned. Opposing batters are hitting just .194 and slugging .306 against his slider.

Boyd’s elite slider helps explain how a pitcher with a pedestrian fastball (91.4 mph average) can become an elite strikeout artist — with a strikeout rate, 11.24 per nine innings, that ranked sixth in baseball entering Friday’s play. All five pitchers ahead of him have harder fastballs — some, such as Houston’s Gerrit Cole, by more than 5 mph.

“His slider has been very tight all year, and he’s gotten a ton of whiffs on that below the zone,” Tigers catcher John Hicks said.

The concept of pitch design, which has overtaken baseball in recent years, may conjure visions of lab coat-wearing scientists pulling new breaking balls out of test tubes — and the truth is only slightly different: They’re pulling them out of computer screens and video readouts.

Boyd’s experience is illustrative. Every offseason between 2014-15 and 2017-18, he trained at Driveline, where the staff use tools such as Edgertronic high-speed cameras and Rapsodo and Trackman data-tracking units to break pitches down into their component parts — grip, velocity, spin axis, horizontal and vertical movement — and reassemble them with diabolical precision.

“It basically boils down to getting a thumbprint of how the pitcher generates” the pitch, said Driveline founder Kyle Boddy, who has worked extensively with Boyd, “and running the metrics through our quantitative model... then getting the [recommended] changes back from the algorithms and [making] those changes.”

With Boyd’s slider, the changes involved first boosting his velocity, which also increased his spin rate, then altering the spin axis to eliminate its slight backspin, which allowed it to gain significantly more vertical depth and horizontal “sweeping” action — about five inches more of each than it had in 2017, according to data at BrooksBaseball.net.

“I’ve always been given these [verbal] cues. Coaches would say, ‘Get on top of the ball.' I’d try to see it, but you can’t really see what’s happening on your fingertips,” Boyd said. “But then I got in front of an Edgertronic camera. [Driveline’s coaches] were showing me, ‘This is the spin you want to create.’ It was like, ‘Oh, I’ve always been trying to do something different.’ ”

All those old tips to “get on top of” his slider? Now Boyd had a visual representation — at 600 frames per second — of what that meant, along with data showing him how those tweaks improved his spin rate, velocity and movement.

“We were watching the baseball come off my fingertips, and I’m watching my whole wrist turn,” Boyd said. “They’re like: ‘Don’t turn your wrist. Think about ripping the side off the ball.’ And now I’m seeing it. It was almost instantaneous. Like, boom, boom, 88. I’d never thrown an 88-mph breaking ball in my life. The camera was what bridged [it]. The coaching cues weren’t wrong. They just weren’t clicking for me on the slider.”

But Boyd’s slider isn’t merely a Dr. Frankenstein product of lab work and data analysis. Beginning with that fateful day in 2012 at Oregon State, he also has benefited from a series of old-fashioned coaching tips.

Two winters ago, lefty James Paxton (now a New York Yankee), a frequent training partner, showed Boyd how “presetting” his wrist — cocking it ahead of time into its release position — boosted the effectiveness of his cutter (a close relative of the slider). Boyd tried it, saw immediate results, honed it at Driveline and posted a 4.39 ERA and 8.4 strikeouts per nine innings in 2018, both career bests to that point.

Then, last July, Tigers pitching coach Rick Anderson began working with Boyd on lengthening his stride, eventually adding about six inches of extension to his delivery, which not only allows him to release the ball closer to home plate but also generates more power. Anderson also preaches the importance of using his fastball to set up the slider.

“He gets me back to the basics with my fastball,” Boyd said. “I’ve gotten a lot of strikeouts on my fastball, too.”

With a 1-year-old at home and another baby on the way, Boyd purchased his own Rapsodo unit this past offseason. The same pitcher who didn’t know how to throw a slider seven years ago now possesses one of the game’s best, and he can tell the difference, both in the data and the feel, between a good one and a great one.

“I used to get wrapped up in every single pitch,” he said. “Now I understand how I feel, what my cues are and what the ball does when it’s going right. When something goes out of whack, I know how to fix it.”

Read more:

MLB, long expecting Latin players to learn English, is finally beginning to speak their language

With No. 1 MLB draft pick, Orioles make catcher Adley Rutschman the centerpiece of rebuild

When it comes to the MLB draft, the Nationals need a turnaround there, too

After foul ball injures girl, does baseball need to do more?

Phillies are content to let Bryce be Bryce, and it’s beginning to pay off at the plate