Valente Bellozo aces MLB debut, but next start will be tougher test

With their depth chart depleted by numerous injuries, the Miami Marlins starting pitcher carousel keeps on spinning. Only halfway through the 2024 season, Miami has already used 14 different starters, including 10 in the last 30 days alone.

The newest addition to that not-so-exclusive club, Valente Bellozo, was arguably the least qualified. When he was acquired via trade from the Houston Astros in April, the Mexican right-hander had just four career games of experience above the High-A level. He had never been invited to a big league spring training camp. During the first half of the minor league campaign, Bellozo split time between Double-A Pensacola and Triple-A Jacksonville, posting ERAs worse than league average at both stops. He wasn't even on the 40-man roster, but the decision to call him up prior to Wednesday's game against the Kansas City Royals speaks to the Marlins' desperation.

What makes baseball beautiful is how unpredictable it can be in small samples. Bellozo's results in his debut were excellent: 5.0 IP, 2 H, 0 R, 0 BB, 2 K, 72 pitches/46 strikes. If not for an abrupt Huascar Brazoban implosion, he would have earned the win.

Bellozo was poised for this special occasion. With their adrenaline flowing, it's common to see a velocity spike from debuting pitchers, coming at the expense of their control. But Bellozo actually threw his fastball a half-tick slower in Kansas City (averaging 91.1 mph) than he did in his Triple-A outings (91.6 mph).

In the bottom of the second inning, Vidal Bruján lost his battle with the sun on what should have been a routine, inning-ending popout. As a result, Bellozo had to pitch with runners in scoring position for the first time. He responded by striking out Garrett Hampson on three pitches, then retiring every batter he faced from that point forward.

With that being said, Bellozo was fortunate to keep the Royals off the scoreboard. Excluding the sun-aided double, he allowed only one hit despite six hard-hit balls against him. His overall batting average on balls in play was .133, which is unsustainable. The Marlins went to their bullpen without letting the rookie begin his third trip through the lineup.

Also worth noting, the Royals conceded the platoon advantage to Bellozo. They started only two left-handed batters, one of whom, MJ Melendez, has had a terrible year at the plate (67 wRC+).

Bellozo is projected to make his next start at loanDepot park on Tuesday against the Boston Red Sox. They are practically tied with the Royals in the AL Wild Card race, but should put up a tougher fight. The Sox have been one of MLB's most consistent offensive teams lately and they typically start seven lefties when facing a right-hander. Bellozo was able to navigate his debut with only a handful of changeups and no curveballs; against Boston, expect to see increased usage of both pitches.

Bellozo's ability to hold baserunners will eventually be tested. His MiLB opponents have gone 11-for-12 on stolen base attempts this season. The Red Sox can be relentless in that department, swiping nine bags on June 16 (the highest single-game total for any MLB team in 2024).

Thanks to an off-day on Monday, the Marlins will have the option of coddling Bellozo again and turning to their rested relief corps before the Red Sox lineup gets too comfortable. Despite launching his MLB career on a very positive note, I'd advise waiting to see what he does for an encore before putting any expectations on him.

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