I don’t know if he’ll ever play for the Diamondbacks again, but there’s a deep drive to left…
- Rating: 3.21
- 2024 Stats: 7 G, 10.1 IP, 5.23 ERA, 3.55 FIP, 1.452 WHIP, 83 ERA+, -0.1 bWAR, 0.1 fWAR
- Date of Birth: April 3, 1998 (26 years old, and just four days younger than the Diamondbacks)
- 2024 Earnings: $713,700 (per Spotrac and B-Ref)
- 2025 Status: Free agent
Introduction
There are various classes of player with extreme difficulties in evaluation. In recent Diamondbacks’ history, I think of the 2016 duo of Chris Owings and Brandon Drury. A pair of infielders with little big league experience, they were called upon to play semi-regularly in the outfield for a team that was going nowhere. Neither put up good numbers at the plate, and both were below-average defensively, although they certainly put a sizeable amount of effort into being good. The bottom line numbers were not good; Drury was replacement level, and Owings slightly above, but that was entirely due to positional adjustments. They were both replacement level players.
But when a replacement is replacement level, is that a bad thing? Two days before opening day in 2016, the regular center fielder was going to be A.J. Pollock. There would have been as much expectation of Micah Owings playing center field as Chris Owings.
Humberto Castellanos is a replacement-type player. Selected off waivers in January of 2021, he made 16 starts for the Diamondbacks over the next two seasons, and was Sir-Not-Appearing-in-2023 thanks to Tommy John surgery in August of 2022.
2024 Overview
Heading into the 2024 season, there was no expectation that Castellanos would be part of the major league pitching staff. He was firmly entrenched in Reno as depth, with there being question marks as to whether he would be able to deliver consistent innings as a starter. With the rotation looking like a strength of the Diamondbacks, and there being plenty of middle relief options, the chances of Castellanos appearing seemed slim.
Through two months in Reno, he got stretched out and delivered consistent innings for the Aces, but the underlying numbers were far from spectacular. He was walking too many batters, and having some BABIP luck.
However, to say disaster struck is an understatement. Injuries to Geraldo Perdomo and Alek Thomas were the first dominoes to fall. That resulted in Corbin Martin being waived and selected off waivers by the Brewers. In mid-April, Luis Frías was placed on the IL. A week later, Merrill Kelly, Miguel Castro, and Kyle Nelson were all placed on the IL on the same day. Yes, new pitchers (Brandon Hughes and Joe Jacques, primarily) were brought in to fill some innings, but the depth was thinning, rapidly. Then, at the end of May, Zac Gallen became the 127th Diamondback to injure his hamstring. (OK, it only seemed like it, but there were a ton of hamstring injuries up and down the organization last season.) Just four days later, news of Andrew Saalfrank’s gambling broke, and all of a sudden, Castellanos found himself as part of the staff.
He relieved Brandon Pfaadt on June 7th for his season debut, and it did not go well. He walked two and gave up five hits and five runs as a 5-0 game turned into a 10-3 rout. He was optioned the next day, with Scott McGough and Tommy Henry coming back from Reno.
Castellanos made two more starts in AAA, one bad and one good. On June 28th, he and McGough traded spots yet again, and he would spend almost a month in the big leagues.
This time, things went well. He made six appearances, worked eight innings, and allowed just one earned run on six hits and two walks. He collected his first career save on July 6th in San Diego, the first of two times that he pitched on consecutive days. He rarely pitched in high leverage situations, though, and when he did, things didn’t go well. On July 21st, he walked in the winning run in the tenth inning in Chicago. His role was simple: a middle inning mop-up guy who might be called upon in high leverage if a game went extra innings, but wasn’t going to be handed key innings with the lead. To drive home the point further, his extra-inning save was the only game in which he appeared that the Diamondbacks won.
He was optioned after his three inning appearance on July 22nd in favor of Jordan Montgomery, designated for assignment on August 11th, and outrighted back to Reno. He continued to pitch decently in Reno for the remainder of the season.
2025 Outlook
Castellanos is unlikely to appear for the Diamondbacks in 2025. He elected free agency on October 14th and likely wants to sign in a place where he would have a chance to earn a rotation spot. That shouldn’t be Arizona, but given how last year went, keeping depth around seems a wise decision. He’s out of options, however, so he really doesn’t seem like a good fit.
Conclusion
This means that his Diamondbacks career can be summed up. He made 32 appearances (16 starts) over four years in the organization. He was replacement level, but he was never more than a replacement player, so that’s to be expected.
While he’ll likely not be remembered a decade from now, every organization needs a player like Castellanos. He may be the first player covered in this series that one can truthfully say that about. His role was far from romantic and unappreciated, but it was still a key role, and it will be interesting (for me, at least) to see who will fill that role in 2025.