Matt Waldron Brought the Knuckleball Back to the Majors

If not as momentous as the rediscovery of the coelacanth after a 65-million-year absence, the return of the knuckleball to Major League Baseball was still an occasion worth noting. On Saturday, the Padres recalled Matt Waldron to make a spot start, and the 26-year-old righty became the first pitcher to throw a knuckleball in a regular season game since the Orioles’ Mickey Jannis in 2021.

Waldron threw only 13 knucklers from among his 62 pitches, mixing the fluttering pitch into a more standard arsenal, but he got good results with the offering. All told, he performed respectably, allowing just two runs — both via solo homers off his four-seam fastball — in 4.2 innings to the Nationals. Unfortunately, the Padres didn’t score at all, and fell 2–0.

Matt Waldron, Knuckleball. ? pic.twitter.com/kpmpuXQKzB

— Rob Friedman (@PitchingNinja) June 25, 2023

Where the knuckleball generally had at least one or two standard-bearers with secure spots in the majors at any time from the mid-1960s up through 2017, the pitch has become an endangered species in recent years, as I’ve noted a few times in this space. Brothers Phil Niekro (who pitched in the majors from 1964 to ’87) and Joe Niekro (1967–88), Wilbur Wood (1961–78), and reliever Hoyt Wilhelm (1952–72) all thrived with the pitch (some for longer than others), with the elder Niekro and Wilhelm both making the Hall of Fame. Charlie Hough (1970–94), Tom Candiotti (1983–99), and Tim Wakefield (1992–93, ’95–2011) became staples of the rotation if not stars, and Steve Sparks (1995–96, ’98–2004) and Dennis Springer (1995–2002) found sporadic success. R.A. Dickey took the baton from Wakefield and gave the knuckleball its last burst of prominence. He turned to the pitch in 2008 after finding little success during his sporadic appearances in the majors from ’01 to ’06, finally solidified a spot in the majors in 2010, and two years later became the first knuckleballer to win a Cy Young Award; that year, he was the only true pitcher to throw a single knuckleball in the majors according to either PITCHf/x or Pitch Info.

Dickey lasted until 2017, when he was 42 years old, but aside from him, every knuckleballer who came and went more or less hung around on the major league margins. Steven Wright, who debuted for the Red Sox in 2013, spent parts of seven seasons in the majors, but a knee injury and a suspension for domestic violence limited him to 60 innings in 2018–19, the first years of the post-Dickey era. Since then, the pitch has become the province of position players pressed into mop-up duty, with Ryan Feierabend (2019 with the Blue Jays) and Jannis the only true pitchers to try it at the major league level. That they combined for just three appearances, allowing 14 runs in nine innings, only underscored the pitch’s decline in popularity.

Hence the interest in Waldron, whom Cleveland drafted out of the University of Nebraska in the 18th round in 2019, then sent to San Diego as the player to be named later in the Mike Clevinger blockbuster in November 2020. Waldron taught himself a knuckleball way back in Little League, figuring it out with twin brother Mike, who had this to say about it when interviewed on MLB’s broadcast:

“[It started] just out of curiosity… It was one of those things that you’re like, ‘Hey, that’s pretty cool. We’ll go ahead and see what we can do, throw it around.’

“It kind of became one of those fun pitches we’d throw around when we were at practice or something, just something to mess around with. To see it work at this level … it’s unbelievable, really.”

Waldron turned some heads in Padres camp throwing the knuckleball in warm-ups in 2021, and so the team encouraged him to feature the pitch, which sat in the low 80s and contrasted well with his 92–94 mph fastball, slider, and changeup. Exactly how much he threw it is unclear, but according to Baseball America, “As Waldron got more comfortable with the pitch, he pushed its usage over 70%.” He pitched to a 4.25 ERA, walking 35 and striking out 103, in 103.2 innings split between High-A Fort Wayne and Double-A San Antonio.

Unfortunately minor league pitch usage data for Waldron isn’t easy to come by, as the pitch is so rare that auto-tagging systems usually label it as a slider or changeup; check out his spin rates for the pitch, and occasionally you’d see one that’s 2,900 RPM or so instead of sitting in the 100–400 range, where he was in his most recent start for Triple-A El Paso on June 16. According to Synergy Sports, which manually tags each pitch, Waldron threw knuckleballs just 9% of the time last year while getting smoked for a 6.26 ERA in 113.2 innings split between San Antonio and El Paso. He walked 39 and struck out 96 but served up 14 homers, including 12 in just 69.1 innings for El Paso. This year, he was up to 22% in his knuckleball usage; based on various reports and his own comments, he was throwing it more often to lefties than righties. “I use it coming out that same tunnel [as the fastball],” he told reporters.

For as sound as his plan may be, Waldron had been rocked for a 7.02 ERA, 5.34 FIP and 11 homers in 66.2 innings when the call came. Those numbers obviously aren’t impressive, but it’s worth remembering that altitude is a significant factor in the Pacific Coast League. The Chihuahuas’ Southwest University Park sits 3,750 feet above sea level; the circuit also includes high-altitude parks in Albuquerque (5,100 feet), Reno (4,500 feet), Salt Lake City (4,230 feet), and Las Vegas (3,000 feet). Not only do batted balls carry further at such altitudes than at sea level, but knuckleballs also move less. Dickey never pitched at Coors Field (and only faced the Rockies twice) but did throw bullpens there and pitched against Triple-A Colorado Springs during his minor league years. In 2012, he explained the hazards of the knuckleball at altitude to sportswriter Dave Krieger:

“It is tougher to throw at those high altitudes because there’s not much humidity for the ball to kind of resist against. At sea level… if I throw a mediocre knuckleball, well, it’s still going to move, it just might not move as sharply or as much. If I throw a mediocre knuckleball in Colorado, it’s going to be a b.p. (batting practice) fastball right down the middle that I’m going to have to either dodge or I’m going to just put my glove up for the umpire to throw me another ball because that one just went 450 feet.

Thus the conditions make it tough to take Waldron’s numbers at face value, which the Padres surely understand when they turned to him for a spot start in place of Michael Wacha; he’s been the team’s best pitcher this year, with a 2.90 ERA and 3.78 FIP, but has also been notoriously fragile throughout his career and is currently dealing with a bout of shoulder fatigue. Waldron’s stay wasn’t expected to be a long one — and in fact, he was optioned back to El Paso on Sunday — but his outing did open some eyes.

Facing the Nationals, who rank 12th in the NL in both scoring (4.13 runs per game) and wRC+ (93), Waldron got ahead of leadoff hitter Lane Thomas using his four-seam fastball, then unveiled the knuckleball on a 1–2 pitch that Thomas fouled off; as it turned out, Thomas would be the only righty-swinger to see any of Waldron’s knucklers. Two pitches later, Waldron struck out Thomas swinging at a 93.8 mph four-seamer right down the middle. After getting Luis Garcia on a first-pitch grounder, he got ahead of switch-hitting Jeimer Candelario (who batted lefty) 0–1, then threw another knuckler, this one too low. Candelario took it for a ball, then crushed a 92.9-mph middle-middle fastball for a towering 395-foot solo homer, 107 mph off the bat, the hardest-hit ball Waldron would allow all evening. Here’s a look at the two knucklers, contrasted with the two payoff pitches:

Ouch. After the homer, Waldron recovered to strike out Joey Meneses to end the inning, using three four-seamers as well as a cutter and a slider, both of which were way outside the strike zone. He kept the knuckleball on ice until the fourth inning, after working around a leadoff single by Corey Dickerson (a lefty) in the second and serving up a solo homer to Thomas on a 92.4-mph first-pitch fastball in the third; he also issued a one-out walk to Garcia but stranded him.

In the fourth, Waldron threw back-to-back knuckleballs to Dickerson, who had fallen behind 0–1; he fouled off both, took a fastball for a ball, then grounded to shortstop on yet another knuckler. Waldron went back to the pitch for three out of the four offerings to the next batter, switch-hitter Keibert Ruiz (batting lefty), who finally grounded one to second base. Here are the floaters from that two-hitter sequence:

While it would have figured that Waldron might throw a knuckleball to lefty Dominic Smith, he didn’t need to, as Smith grounded out on an 0–2 fastball. In the fifth, righty Derek Hill grounded to short on a fastball after laying off two cutters well outside the zone. Lefty CJ Abrams, on the other hand, saw nothing but knuckleballs, flying out to right field on the fourth one.

That swinging strike had 20 inches of horizontal movement, Waldron’s highest measure of the game and one of four in double digits. Here’s a slow-motion view:

Matt Waldron, Knuckleball Movement. ?

20 Inches of Run. pic.twitter.com/oS3dce5VPd

— Rob Friedman (@PitchingNinja) June 25, 2023

Thomas took Waldron’s final knuckler for ball one before singling off a slider, at which point manager Bob Melvin pulled the rookie in favor of veteran lefty Tim Hill, who struck out Garcia. The Padres bullpen didn’t allow another run, but the lineup couldn’t muster any kind of heat, managing just four hits, all singles, and failing to take advantage of an additional four walks against starter Josiah Gray. The Nationals bullpen retired all 11 batters it faced, six by strikeouts.

All told, Waldron threw 27 four-seamers, 14 sliders, seven cutters and a sinker to go with his 13 knuckleballs. He got five whiffs and 10 called strikes with the four-seamer, which averaged 92.3 mph and topped out at 94.4. He got just one whiff out of seven swings via the knuckler, whose velocity ranged from 76.3 mph to 84.2 mph, as well as two called strikes; he had a 23% CSW for that pitch, compared to 37% for the fastball and 29% overall. Batters did chase three of the eight floaters he threw outside the strike zone (37.5%, and it’s worth noting that none of them escaped the reach of catcher Gary Sánchez, who was handling the pitch for the first time), but they also made contact with all five in the zone, though the only ones they put into play were the outs of Dickerson, Ruiz, and Abrams. Those three had an average exit velocity of 89.7 mph, an xBA of .137, an xSLG of .160, and an xwOBA of .125, though his overall marks — 92.2 mph exit velo, .294 xBA, .574 xSLG, .383 xwOBA — obviously weren’t as good. As his 50% hard-hit rate and 6.35 xERA attests, Waldron needs to do a better job of limiting hard contact if he’s to survive.

As for the knuckleball itself, the total of 13 that he threw on Saturday was fewer than those of seven position players who have broken it out for their mound cameos during the pitch-tracking era (2008 onward), not to mention all nine of the other pitchers who did so. Excluding the bastard sons of Wade Boggs, here’s how they stack up:

Waldron’s knuckler rates as the fastest in terms of average velocity, faster even than Dickey’s “angry knuckleball.” It’s mid-pack in terms of vertical movement, but tops in terms of horizontal movement. Unfortunately, I don’t have much in the way of direct comparisons for spin rate, since it wasn’t until Statcast switched to the Hawkeye cameras in 2020 that spin could be measured directly; Waldron’s knucklers averaged 295 RPM, which is lower than Jannis’ average of 407 but about double the ideal of 150, which translates into about one to one and half rotations from the mound to the plate. Neither Stuff+ nor PitchingBot even scored Waldron’s knuckleball, though both models really liked his slider (whose usage rate matches up with Gameday, which is to say the pitches aren’t being conflated), and PitchingBot found his other pitches to be at least average, though it didn’t score the cutter. Stuff+ saw his other pitches as pedestrian, which I believe better matches up with the general scouting perception. Small-sample caveats abound:

All told, I think it’s fair to say that Waldron demonstrated some promise with the way he used the knuckleball to keep hitters off balance, but that unless he can hone his arsenal and find a way to miss more bats, he’s likely destined to remain on the fringe of the majors rather than securing a regular job. I would absolutely love to be wrong about that, because even in his one-night cameo, Waldron’s knuckleball was a most welcome sight.