5 MLB Pitching Prospects Impressing In The Arizona Complex League

Image credit: Argenis Cayama (Photo by Bill Mitchell)

Argenis Cayama knew something was off—he just didn’t know the gravity of his situation.

The Venezuelan pitcher was about to wrap up his first month of workouts ahead of the start of the Dominican Summer League after signing with the Giants in 2024, when suddenly he felt ill.

His body temperature? Scorching. Chills? Running through his body. And his cough? Uncontainable.

Cayama thought he’d feel better as time passed. Instead, it only worsened. Getting out of bed became a chore. Walking left him breathless. Breathing itself hurt.

After realizing the severity of his condition, he visited a doctor and was diagnosed with pneumonia. Cayama was sidelined for about a month and lost 18 pounds in the process.

Even more concerning, however, was the decrease in his velocity. Cayama’s fastball had previously sat around 92-95 mph. When he returned, it was between 80-83 mph.

“I felt alone,” Cayama said in Spanish to Baseball America. “My family wasn’t with me. It was me vs. this illness. But I just kept pushing with my treatment plan the Giants gave me. It was tough in the moment, but I knew that when I was ready to return, I’d come back strong.”

Strong indeed.

After missing the first three weeks of the season, Cayama posted a 2.59 ERA with 29 strikeouts across 24.1 innings in the DSL last summer. The velocity was regained, and so was his confidence.

“It was incredible,” Cayama said. “It was all glory to God, man. Without him, none of this would have been possible.”

Now, Cayama is carrying that same grit and growth into the Arizona Complex League, establishing himself as one of the top arms in the circuit. Through his first three starts, the 18-year-old righthander hasn’t allowed an earned run across 11.1 innings. Opponents are batting just .132 against him.

He’s doing it with a fastball that now sits 92–98 mph and comes with plenty of shape. His go-to secondary pitch is a confident slider, and he’s been steadily refining his changeup. He’s also added a sinker he says he feels good about.

Cayama’s production is especially encouraging considering he only transitioned to the mound a little under two years before the Giants signed him for $147,500.

“My mentality is to get outs,” Cayama said. “The pitcher that gets paid the most is the one who gets the most outs. As long as I keep attacking the zone, the hitters will stay guessing.”

Cayama’s growth isn’t just physical—it’s mental, too. He’s learning not to let his emotions control him on the mound. He’s trusting his mix more, not over-relying on the fastball. Every outing is another step forward, both in results and in maturity.

But as great as his desire is to one day pitch in the majors, Cayama cares more about putting himself and his family back home in Venezuela in a position to succeed, especially given the ongoing crisis in his native country.

“I just want to represent my family,” Cayama said. “But not just them—I’m trying to show that good things can come out of Venezuela.

“This is so important to me, I take it very seriously.”

Cayama isn’t the only pitcher turning heads in the desert. Across the Arizona Complex League, several young arms are off to promising starts this spring. Here are four more pitchers making early noise in the ACL.

Jostin Florentino, RHP, Cubs

Florentino continued to impress with his command during extended spring training, reinforcing the reputation he established over two standout seasons in the Dominican Summer League. There, he racked up 75 strikeouts against just 20 walks and allowed only two home runs—a testament to his ability to keep the ball in the yard. That knack for pounding the strike zone has carried over into the Arizona Complex League, where the 20-year-old is navigating the expected learning curve but still demonstrating the same sharp control.

Mathias LaCombe, RHP, White Sox

LaCombe is 22 years old, which would normally be considered old for the ACL. But he’s not your typical, freshly-drafted prospect. Originally from France, LaCombe honed his craft overseas before moving to Arizona and pitching at Cochise Community College. His fastball sits comfortably in the mid 90s, and he pairs it with a sinker-slider combo. He experimented with a sweeper during instructs last year. The results have been eye-opening, and his 21 strikeouts are currently tied for the league lead. The White Sox clearly saw something they liked, grabbing LaCombe in the 12th round and signing him for $450,000—money usually reserved for a fifth-rounder.

Payton Martin, RHP, Dodgers

After allowing nine earned runs across 11.2 innings in three starts at High-A Great Lakes, Martin was reassigned to the ACL to iron out some wrinkles. Since arriving in the desert, the 21-year-old allowed just one earned run across 14 innings, striking out 17 batters while issuing zero walks. Martin is throwing with a ton of spin and has an arsenal that includes a fastball in the low-to-mid 90s. The righthander was primarily a shortstop in high school before the Dodgers signed him for $125,000 in 2022.

Luis Pimentel, RHP, Reds

As mentioned before, the Reds have an excellent crop of pitchers. Stharlin Torres, for example, earned a spot on last week’s under-the-radar list and was also the helium player on this week’s Hot Sheet. Pimental was also in the mix to be featured, and he gets a well-deserved nod here. He didn’t allow a run over his first two outings (eight innings) and filled up the strike zone with ease. In his debut, he struck out seven. In his second start, he didn’t notch any punch outs, but logged nine outs on ground balls. That seems to be his calling card when he’s not blowing hitters away with his fastball. So far in 2025, he’s pitched to a 1.50 ERA with 12 strikeouts and just one walk.