O's lefty De León (and his personal catcher) building on momentum in Fall League

From the start of August through the end of the regular season, Orioles left-hander Luis De León was one of the hottest pitchers in all of Minor League Baseball. Through a week and a half of the Arizona Fall League, he’s also one of the hottest pitchers in the desert.

Those who’ve seen him most aren’t surprised.

“It’s the same old De León,” Baltimore catcher Ethan Anderson said.

Ranked the No. 21 prospect in the O’s system, De León posted a 1.47 ERA and an 0.95 WHIP over his final seven outings (36⅔ innings) between High-A Aberdeen and Double-A Chesapeake. His 59 strikeouts were tied for fourth-most in the Minors since Aug. 1 with the Marlins' Thomas White -- the top southpaw pitching prospect in baseball.

Now in the Valley of the Sun, the 22-year-old hurler has made two starts with Peoria and has been just as dominant, following another 4⅓-inning gem Thursday at Mesa. He has a 1.08 ERA and an 0.96 WHIP with 12 punchouts over 8⅓ frames (most in the Fall League).

After De León opened the season on the Aberdeen injured list for a month, this hot run is a sign of a pitcher peaking at the right time and a culmination of something that began long before August.

“I think for him [it’s] all the little things -- the preparation, the daily work, all those things took a step to the next level,” said Peoria pitching coach Jeremy Hileman, who spent time with De León at Aberdeen this summer. “I think it really, really carried over into his performance, and I think he found a little consistency in that and a few good performances. I think he just kind of caught his footing again and has run with it since.”

The proof is in the pudding, or rather the arsenal.

The 6-foot-3 pitcher is largely a sinker-slider pitcher, but both pitches flash comfortably plus. The sinker largely sat 95-97 mph Thursday with 16-20 inches of armside run, giving it heavy movement on top of impressive velocity. The slider comes in at 84-88 mph and with tighter movement with 0-7 inches gloveside. That difference and his command of the breaker is enough to keep hitters consistently frustrated -- Mesa batters swung at 14 sliders and missed on nine of them for a whiff rate of 64 percent.

“To be honest with you, that was one of my worst pitches when I started the year,” said De León via interpreter and Peoria manager Julio Morillo after winning AFL Pitcher of the Week honors for Week 1. “But I kept working on that pitch with my pitching coach during the season, and thank God everything has been working well for me. Like my pitching coach says, keep it fast and keep it short, and I think that cue has worked for me a lot.”

“Obviously when you throw 97 or 98, it helps everything else play up too,” Hileman added. “But I think him locating [the slider] to good zones and throwing it hard, that's all he really needs to do, and it's going to be a good day if he's doing that.”

De León also works with a four-seamer for a different heater look with more ride, and his upper-80s changeup has enough separation and horizontal movement (19-21 inches) to flash plus as well. He’s worked on adding an 83-86 mph splitter with even less spin and more drop than the cambio as well.

“It's something different to throw at hitters,” Anderson said. “If they're thinking, 'Hey, I have to play this east-west game with the sinker going away from me or slider coming into me,' and then all of a sudden, you're throwing a splitter that's dropping straight down 15 mph slower, it's going to be a really tough at-bat.”

Anderson first caught De León on Sept. 3, 2024 with Aberdeen, roughly two months after the backstop was taken in the second round out of the University of Virginia. He moved behind the plate for his junior year with the Cavaliers and was still continuing his catching education in the O’s system when they crossed paths. They were back together with the IronBirds this season, up with Chesapeake upon De León’s promotion in late August and now with Peoria in the Fall League.

“All his stuff moves a ton, so it took some adjusting to catch him,” Anderson said, “but I've caught him so many times. We don't speak the same language. I speak a little Spanglish, and he mixes in a few words there. But I feel like we're on the same page.”

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The numbers -- both in terms of results and pitch analytics -- back up that the partnership has worked wonders on both sides of the Mississippi in 2025. With De León’s continued dominance and Double-A finish to the year, it seems like Baltimore could be within reach by the second half of 2026. Anderson wouldn’t mind O’s officials remembering how the pair works as a battery by then.

“I told him that I'm his personal catcher,” Anderson said, “and he has to take me to the big leagues with him.”