This article is part of a series taking a look into individual Diamondbacks player projections as we head into 2024 spring training. The projections presented are a composite of the rate (percentage) stats from Steamer and ZiPS as published on FanGraphs. The playing time projection is our own, and is based on the current roster as of the time of this writing. Further roster changes will impact the playing time and thus the WAR projection, but not the rate or percentage statistics presented.
Miguel Castro had a tumultuous 2023 campaign, coming over to the D-backs from New York in the prior off-season. The hard-throwing reliever saw plenty of action, mostly in later innings, and serving as a part-time closer before the acquisition of Paul Sewald.
Castro had a tremendous start to his season, pitching to a 2.22 ERA over his first two months. However, he struggled from June-August, ballooning his ERA well past 5.00, while being responsible for five losses and three blown saves.
He had a resurgence in September, and for the final stretch of the regular season, he didn't allow an earned run in 11 full innings, with a 16/2 K/BB in that time.
However, he was rough again in the playoffs, allowing seven runs in six innings, including a walk-off home run in Game 1 of the World Series and a brutal outing that helped put Game 4 out of Arizona's reach.
Castro's projections don't look too different from his 2023 numbers. They do expect a slight improvement in ERA and FIP, as well as increased strikeouts, but the improvements are marginal at best.
Our playing time projections expect him to take on a decent workload, but nothing close to what was being asked of him in 2023. A 4.10 ERA isn't anything terrible, and the other numbers are certainly respectable outside of another somewhat high walk rate, with a moderately better year projected ahead of him.
ZiPS expects an ERA below 4.00, whereas Steamer looks for him to land much closer to his 2023 number. Both systems expect a similar level of home runs allowed per nine, but his batted ball luck looks to be significantly worse, due to a return to the mean in that category.
Why Castro might outperform this projection
Castro is an imposing 6-foot-7, with killer movement and velocity in his arsenal, consisting of a sinker, slider and changeup.
All three pitches sport above-average movement, and his sinker tops out around 97mph. This leads to a profile that can be impressively strikeout-heavy, but he still ranked in the top 10% of MLB in average exit velocity and hard-hit rate. He sat in the 80th percentile in barrel rate, and his 82nd percentile extension allows for his high movement and deception.
He was at least above average in each metric, and with some work on his control, his pitches can be absolutely devastating. As with many of the D-backs' very taxed pitching staff in 2023, extreme necessity for clutch relief and overuse could have helped spike Castro's numbers.
In high leverage, he was shaky, but his low leverage average against sat at .170 with a .255 slug attached. With bases empty, Castro was similarly excellent, with a .173/.266/.268 slash.
A more relaxed role, with a solidified pen to lock down the later innings could help Castro greatly overachieve these numbers and be a much more effective middle inning or spot reliever.
Why Castro might underperform this projection
Inconsistency has been the story of the right-hander's career. One month he's dealing, the next he's allowing a 10.00+ ERA. Due to his movement, his pitches produce a decent amount of soft contact, but his tendency to either walk batters or leave pitches hanging over the plate has been his downfall.
His K/BB was a below-average 60/25, and he did increase his tendency to allow home runs in 2023. Since he demonstrated a lack of ability to pitch well in the clutch, his role could be reduced to clean-up situations, and you never know when a blowup outing could occur.
Although only 29, Castro has been in the majors for nine years, and although he's had some very solid overall seasons from an ERA perspective, he's always had an issue with lopsided innings and control.
There's a world in which the control doesn't improve, as has been the pattern, and these numbers negatively spike even more.
Summary
Castro has been a rough watch for D-backs fans, despite flashing some potential and showing a deadly arsenal. Castro could easily lock in and exceed these numbers in a lower-pressure, lower-use role, but his inconsistency could flare up again, and if the control doesn't improve, we could see him continue to walk guys and leave balls hanging over the plate.
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