Quinn Mathews is hereby interesting, some encouraging Alec Burleson comps, and the psychic burdens of Nolan Arenado

Let's talk about this team that is four games above .500

Here’s what I’m thinking about this week insofar as our Cardinals are concerned …

Quinn Mathews might be a dude 

We should all probably start paying more mind to Quinn Mathews. The 23-year-old lefty out of Stanford (fourth round, 122nd overall, 2023 draft) recently earned a promotion to Double-A. It’s notable anytime a former major-conference Friday starter and high-ish draft pick reaches the upper rungs of a system, and in Mathews’ case it’s even more so. That’s because of his current trajectory. 

Mathews didn’t make his pro debut until the current season because the Cardinals opted to put him on ice for the remainder of 2023. That was in response to his alarmingly heavy workloads at Stanford, which included a 156-pitch complete game (!) against Texas in the super regional. Division-I aces are almost always fast movers, but what Mathews has done this season exceeds even those standards. 

The Cardinals started him out at Single-A Palm Beach, and he was roundly dominant across six starts and 30 ⅔ innings: 1.47 ERA, 2.20 FIP, 44.4 K% (!). After barely a month in the Florida State League, Mathews was bumped up to High-A Peoria in the Midwest League. In seven starts/43 ⅔ innings at that level, he authored a 2.68 ERA, 2.31 FIP, and 35.7 K%. In yet another sign of Mathews’ dominance, Adam Sanford of Down on the Farm notes this: 

“Among the 168 minor league pitchers with at least 60 innings pitched this season, Mathews has the highest whiff percentage (18.1%); the next closest is Brandon Sproat with 16.4%.”

There’s leading an important statistical category, and then there’s taking full ownership of it. This is an example of the latter. 

Mathews was plainly not being tested in Peoria, so before the calendar flipped to July the Cardinals elevated him to Springfield of the Texas League. That’s three levels in as many months, all in his first professional season. He’s only made one mixed-bag start at Double-A by this writing, but it wouldn’t shock anyone if Mathews pitches at four different rungs this year, which would put him in the discussion for a 2025 rotation spot (depending upon how the Cardinals handle their club options on Lance Lynn and Kyle Gibson). 

With Mathews, though, it’s more than “just” the rapid advancement and general dominance. First there’s his fastball velocity. Coming out of the draft, he was sitting 90-92 with his four-seamer. After an offseason focused on adding bulk and strength and letting his arm rest, he’s enjoyed some gains on that front. Thus far in 2024, Mathews is averaging 94.8 mph with his four-seamer with a 95th-percentile velo of 96.3 mph. Of note is that the average lefty fastball in the majors this season checks in at 93.7 mph, so Mathews has sat a tick or so above that baseline. As well, Mathews’ fastball this season has an effective velocity of 95.1 mph, which generally means he gets good extension off the mound, which in turn makes hitters perceive his fastball as being even more hasty. That’s compared to an average lefty effective velo of 94.2 mph in the bigs this year. 

There’s another reason to be bullish on Mathews’ fastball, and that’s induced vertical break (IVB). This is basically the pitcher’s capacity to create the illusion of “rise” on his fastball, which in reality means the pitch drops more slowly than the hitter expects and thus adds an important layer of deception. Baseball America lays out the standards for such pitch qualities: 

“Four-seam fastballs all have a positive IVB number, an above-average induced vertical break number is 18 inches or more. Pitchers capable of reaching 20 inches of IVB are considered to have elite vertical movement on their fastball.”

Mathews this season has an IVB of 17.9 inches, which means he’s effectively in optimal territory. The average IVB in the majors this season is 15.8 inches. If Mathews were in the majors, then his IVB would rank eighth among qualifying pitchers and fourth among qualifying lefties behind just Tyler Anderson (20.0 inches of IVB), Nestor Cortes (19.4 inches), and Carlos Rodón (18.0 inches). 

So Mathews fastball now has above-average velocity backed by a good plate-ward extension and solidly above-average IVB. Those are the ingredients of a plus fastball, and that’s of course important even in his era of fastball de-emphasis. Not surprisingly, Mathews’ fastball has been beastly thus far: 38.9% K rate versus a 2.8% BB rate and an expected FIP of 1.61. He’s also got a swinging strike rate of 15.7% on the fastball this season. The average for lefties in the minors for 2024 is 10.5%. 

As for the secondaries, they’re also encouraging. Mathews has a stuffed mix of five pitches, but after his lead fastball he leans on the slider in platoon-advantaged situations and the changeup against right-handed hitters. This is a standard approach, and it’s worked well so far. In those favored spots, each pitch boasts sky-scraping K%s and swinging-strike rates. Mathews will obviously need to prove himself in the high minors, but there are lots of reasons to be encouraged. 

If there’s a concern moving forward, at least besides his history of heavy workloads as an amateur, it’s that he may be a bit too fastball-reliant by current standards. He’s thrown the four-seamer roughly 40% of the time to both righties and lefties, and he may need to ease back a bit against more advanced competition. Given the strengths of his slider and changeup, I’d like to see him use those pitches more often in non-traditional spots – i.e., throwing the slider to righties and trying out some lefty-on-lefty changeups. Hitters these days crave fastballs more than ever because it’s just about the only pitch on which they can consistently do damage. It’ll be interesting to see if Mathews adjusts his current approach against Double-A and eventually Triple-A hitters. 

I’d still call Tink Hence the best pitching prospect in the system given his stuff and the fact that he’s thrived against Double-A competition as a 21-year-old. Mathews, however, is entering that particular discussion, and he’s thus far looking like a developmental success story for the Cardinals. Fortunately, we’ll be able to see both Hence and Mathews in the upcoming Futures Game. Beyond that, whether Mathews is able to continue blowing away hitters at Springfield will be one of the most compelling farm-system subplots around. 

In continuing praise of Alec Burleson