When Matt Waldron made his major league debut for the Padres last June 24, it was a noteworthy event. While a few position players had thrown the occasional knuckleball ast a goof after taking the mound for mop-up duty, no true pitcher had thrown one in a regular season game in two years. The last one who had done so, the Orioles’ Mickey Jannis, made just one major league appearance.
Mixing his knuckler in with four other offerings, Waldron bounced between the minors and majors for a couple months before sticking around in September. Now he’s a regular part of the Padres’ rotation, and he’s having success… some of the time. Through six starts totaling 31 innings this season, Waldron owns a 4.35 ERA (111 ERA-) and 4.06 FIP (103 FIP-), which won’t put him in contention for the Cy Young award but is respectable enough to keep him occupying a back-of-the-rotation spot. For what it’s worth, within the Padres’ rotation he’s handily outpitched both Michael King (5.00 ERA, 6.30 FIP), whom the Padres acquired from the Yankees as one of the key pieces in the Juan Soto trade, and Joe Musgrove (6.94 ERA, 6.59 FIP), who last year signed a $100 million extension.
Waldron is striking out a modest 19.7% of hitters but walking just 7.3%; his 12.4% strikeout-walk differential is second best among Padres starters behind only Dylan Cease’s 18.7%, and Waldron’s 1.16 homers per nine sits in the middle of the pack among their starting five (which also includes Yu Darvish) — and a vast improvement on his 1.67 allowed per nine at Triple-A El Paso in 2022–23. He’s done a very good job of limiting hard contact, with his 87 mph average exit velocity placing in the 78th percentile and his 33.3% hard-hit rate in the 75th percentile.
For those unfamiliar with Waldron’s back story, Cleveland drafted him out of the University of Nebraska in the 18th round in 2019, then sent him to San Diego as the player to be named later in the Mike Clevinger-for-Josh Naylor blockbuster in November 2020. The following spring, Waldron caught the Padres’ attention by throwing a knuckleball in warm-ups; he and his twin brother Mike had figured out how to throw the pitch way back in little league. The Padres encouraged Waldron to feature the pitch, and remained patient with him as he took his lumps. In 2022, he was hit for a 6.26 ERA and 5.05 FIP in 113.2 innings at Double-A San Antonio and at El Paso while throwing the pitch 9% of the time.
Last year with El Paso, Waldron threw the knuckleball about 22% of the time before first being called up in June. He was rocked for a 7.31 ERA and 5.44 FIP in 92.1 innings total innings at Triple-A; he improved his strikeout rate from 18.8% in 2022 to 23.8% in ’23, but also served up 1.75 homers per nine. Obviously, those aren’t good numbers, but it’s worth remembering that altitude is a significant factor in the Pacific Coast League, not only in El Paso, where the Chihuahuas’ Southwest University Park is 3,750 feet above sea level, but also in Albuquerque (5,100 feet), Reno (4,500 feet), Salt Lake City (4,230 feet), and Las Vegas (3,000 feet).
Batted balls carry further at such altitudes than at sea level, and knuckleballs also move less. Had Waldron been hit as hard in the majors as he was in the minors, he wouldn’t have lasted long. But while he did turn in some clunkers, he allowed just five runs in 17 innings over his final three outings against the A’s, Cardinals, and Giants — not exactly offensive juggernauts, but major league teams nonetheless. He finished the 2023 season with a 4.35 ERA (105 ERA-) and 5.46 FIP (126 ERA-) in 41.1 innings.
In the majors last year Waldron threw the knuckler 26.7% of the time, but this season, he’s up to 35.4%. Already he’s become just the sixth hurler of the pitch-tracking era — that is, since 2008 — to throw at least 100 knuckleballs, though he’s the first to get to that point while throwing the pitch less than two-thirds of the time. Thanks to Statcast, we know that the 27-year-old righty throws the pitch about as hard as R.A. Dickey, the last prominent knuckleballer.
Knuckleballers in the Pitch-Tracking Era
| Pitcher | Yrs (Career) | Yrs (Tracking) | # | % | Vert | Horiz | Avg. Velo |
|---|---|---|---|---|---|---|---|
| Tim Wakefield | 1992–2011 | 2008–2011 | 7,756 | 82.7% | 61.6 | 2.8 | 65.9 |
| R.A. Dickey | 2001–2017 | 2008–2017 | 22,579 | 80.4% | 45.1 | 0.1 | 76.7 |
| Steven Wright | 2013–2019 | 2013–2019 | 4,201 | 75.0% | 49.1 | 1.0 | 75.1 |
| Eddie Gamboa | 2016 | 2016 | 166 | 74.8% | 53.0 | 3.9 | 70.7 |
| Charlie Haeger | 2006–2010 | 2008–2010 | 729 | 67.9% | 50.2 | 0.9 | 71.2 |
| Matt Waldron | 2023–2024 | 2023–2024 | 376 | 30.7% | 50.1 | 4.6 | 76.6 |
Aside from Wright’s last gasp — 6.1 innings sandwiched between an 80-game PED suspension and a toe contusion, followed by Tommy John surgery — the only other pitcher to throw at least 50 knuckleballs in the majors over the last half-decade was Ryan Feierabend, who made two appearances for a total of 5.2 innings with the Blue Jays in 2019. From this group, Waldron’s knuckler is the first for which we have direct measures of spin thanks to the upgrade from the radar-based Trackman system to the optical-based Hawk-Eye system, which happened in 2020.
For the games that we have such data — all but Waldron’s first two starts of this season — he’s averaged 276 RPM with the pitch. If I’ve done my math right, and that’s a load-bearing if, that translates to about 2.2 revolutions of the ball between his release point and the plate. According to physicist Alan Nathan, who was crunching the numbers using Trackman, Dickey’s knuckler was on the order of 150 RPM, which translates to about 1.5 revolutions between release and home plate.
With less reliance upon the knuckler, Waldron comes to the table with a more complete arsenal that includes both a four-seamer and a sinker, as well as a sweeper and a cutter. His mix varies depending upon the batter’s handedness:
Matt Waldron Pitch Mix, 2024
| Pitch | Velo | vs LHB | vs RHB | Total |
|---|---|---|---|---|
| Knuckleball | 76.7 | 39.7% | 31.5% | 35.4% |
| Four Seamer | 90.6 | 23.2% | 16.8% | 19.0% |
| Sweeper | 78.2 | 15.7% | 22.0% | 19.0% |
| Sinker | 90.2 | 8.6% | 25.2% | 17.2% |
| Cutter | 86.8 | 12.7% | 4.5% | 8.5% |
Our pitch modeling metrics don’t grade Waldron’s knuckleball — they don’t have any real basis of comparison — and don’t think much of his other offerings save for his sweeper, which is graded as a slider by both Stuff+ and PitchingBot. The models do appreciate his command:
Matt Waldron’s Stuff+ and PitchingBot Grades
| Stf+ FA | Stf+ SI | Stf+ FC | Stf+ SL | Stuff+ Location+ | Pitching+ |
|---|---|---|---|---|---|
| 60 | 81 | 87 | 119 | 86 | 102 |
| 33 | 41 | 37 | 51 | 38 | 63 |
| 54 |
The fringy nature of Waldron’s non-knuckleball pitches is somewhat secondary to the element of unpredictability. Most hitters haven’t faced the fluttering pitch before, and its speed and movement contrast greatly with his other offerings — though ideally, he throws the knuckleball so that it mimics the early path of his fastballs. “I use it coming out that same tunnel,” he said after his debut last year.
This year, Waldron is throwing the knuckler on the first pitch of a plate appearance 42% of the time, with the four-seamer and sweeper both at 22.6%, the sinker at 16.8%, and the cutter at 7.3%. When he’s ahead in the count, his usage of the knuckler rises to 48.1% (58.1% against lefties, 38.8% against righties), and when he’s behind it falls to 16.3% (15.9% for lefties, 16.7% for righties), with the sweeper (25%), sinker (23.3%) and four-seamer (20.9%) all pretty equally distributed.
Batters hit .242 and slugged .485 against Waldron’s knuckleball last year; this season, he’s held them to a .163 AVG and .302 SLG against it, and his whiff rate has increased from 24.7% to 25.8%. He’s faring better with his four-seamer than he did last year (.259 AVG/.519 SLG in 2023,…
