Arizona Diamondbacks 2024 Player Review: Miguel Castro

The right-hander's rocky D-backs tenure came to an end in 2024.

Jul 22, 2024; Kansas City, Missouri, USA; Arizona Diamondbacks relief pitcher Miguel Castro (50) pitches during the fourth inning against the Kansas City Royals at Kauffman Stadium. Mandatory Credit: Jay Biggerstaff-Imagn Images / Jay Biggerstaff-Imagn Images

This article is part of a series chronicling the individual seasons of players that appeared for the Arizona Diamondbacks in 2024.

Reviews for players that still have rookie eligibility for 2025 will appear in our prospect season reviews. Players are presented in the reverse order of their aWAR, an average of Baseball Reference and FanGraphs WAR.

RHP Miguel Castro

2024 Contract status: Vesting option, $5 million

Miguel Castro 2024 and career statistics / Alex D'Agostino | Diamondbacks On SI

An up-and-down 2023 saw right-handed reliever Miguel Castro both dominate and struggle. D-backs fans know the struggles all too well. After making 75 appearances (a career high) in 2023, Castro's $5 million vesting option was activated, and he returned to the club in 2024.

But with the emergence of Ryan Thompson, Kevin Ginkel and Paul Sewald in the 2023 Postseason, there was hope that the right-handed fireballer could see success in a lower-leverage role, and come into his own as depth piece for the D-backs' middle relief.

But Castro was never able to make an impact in 2024, or at least show enough improvement to consider him a worthy investment.

Castro began the year on Arizona's active roster. He tossed a scoreless inning against the Rockies on Opening Day, but struggled through the month of April, pitching to a 5.87 ERA over seven appearances, surrendering 12 hits and five earned runs over just 7.2 innings.

After making just those eight appearances, he was placed on the Injured List with right shoulder inflammation. That injury kept him down a full month, after which he was sent to the minors for a rehab assignment.

He spent time in in the Arizona Complex League, then made a handful of appearances with the Reno Aces in Triple-A. The rehab process was quite lengthy, and he eventually made his return to the D-backs on July 11, nearly three months after being placed on the 15-day IL.

He would only make three more appearances for Arizona. He pitched a scoreless inning against the Blue Jays, then pitched a pair of two-inning appearances against the Royals and Nationals.

In those two outings, he allowed seven total hits - including two homers - two walks, and four earned runs over just four innings.

At the July 30 Trade Deadline, the D-backs swung a last-second trade for Nationals reliever Dylan Floro, to take on some of the middle relief workload. Castro was then designated for assignment as a corresponding move to free up a roster spot for Floro.

Just one day later, Castro cleared waivers, and the veteran was outright released by the Diamondbacks. He ended his 2024 campaign with a 5.93 ERA and 1.68 WHIP.

Granted, it was in a somewhat small sample size, but it wasn't just the numbers that looked grim for the righty. Castro's biggest weapon was his sinker. While he struggled with command as a whole with the D-backs, the sinker's movement and velocity made it a weapon regardless.

In 2023, Castro averaged nearly 97 MPH on the sinker. In 2024, it was down to a mere 94.6 MPH, and the arm-side movement on the pitch decreased from 17.5 inches to 16.1 inches.

Whether that is simply due to his injury, or other factors at play is unknown, but Castro simply wasn't able to miss bats in 2024, and the decrease in velocity created a much more hittable pitch for opposing batters.

And so Castro's time with the D-backs came to an end. While his raw stuff certainly gave him potential to contribute in Arizona's bullpen, his inconsistency of both command and velocity led to a tumultuous couple of seasons with the club, as the D-backs' relief corp continues to develop and change.

2025 Outlook

2025 Contract status: Free agent

Castro remains unsigned. It's not impossible to see him return to the D-backs, perhaps on a minor league deal for depth purposes, but it doesn't seem likely that Arizona will return to that well anytime soon.

He doesn't turn 30 until Christmas Eve, December 24, but has already spent parts of 10 seasons in the majors. It's possible that wear and tear has caught up to him for good, though it's not unlikely that another team could take a chance on him again. For now, his time with the D-backs has expired, and it doesn't appear that he'll return to the desert.