Three Diamondbacks Pitchers Who Could Outperform Projections

Which arms are best poised to pitch above expectations?

We've examined the individual player projections for each Diamondbacks pitcher and position player, with a case for both over- or underperformance. However, a few pitchers stood out in their underlying metrics and career patterns, and extenuating circumstances might have contributed to inflated numbers, which, in turn, inflate projections.

One thing to consider with most pitchers, especially in relief roles, is the fact that the D-backs' ability to put together a more whole bullpen with defined roles will be a necessary boost to the entire pitching staff. Overwork, role cycling and closer woes contributed to a first half that set up some of Arizona's arms for failure, or worked them to the point of a decrease in control--and even injury.

Here are the three pitchers that could potentially have the highest ceiling to pitch above their projected numbers in 2024.

1: RHP Zac Gallen

Projection: 185 IP, 3.69 ERA, 6.8% Walk, 23.6% Strikeout, 3.4 aWAR.

The D-backs' ace has a slightly concerning projection line, with a worse ERA, walk rate, K rate, home runs per nine (1.10) and overall average WAR to his 2023 season.

2023 was pretty much considered a down year for the right-hander, but his numbers as a whole showed a very strong season, and he pitched extremely well in some critical starts throughout the year.

So why might this projection be low-balling him a bit?

Gallen has a history of improvement, and, outside of a rough year on all fronts in 2021, has pitched well below a 4.00 ERA every year as a major leaguer. The tricky part of 2023 came from his usage. Although it's reasonable to expect a near-200 inning load for an ace, Gallen pitched 210 innings, 26 higher than his previous career high...in the regular season alone.

Add another 33 2/3 innings in a high-adrenaline postseason, and Gallen pitched roughly 10 more starts in 2023 than he had ever pitched before. While you can't make excuses for poor performance, the truth is Gallen still pitched well in 2023, but where his issues began to arise came from frequent hard contact, which became more frequent as the season grew old.

As fatigue likely began to set in, it's not out of the question to attribute control issues to the marathon season. 

As Gallen's control decreased, we saw an increase in his walks (which still remained at an 88th percentile level), but also a tendency where he seemed to rely a little too heavily on his fastball, which stopped dotting the zone and started sailing or sitting out over the plate, while only hitting around 93 MPH regularly. Batters weren't so easily fooled by the breaking or off-speed pitches, since the fastball wasn't as reliable a weapon or setup pitch.

His 2023 Statcast metrics were anomalous to his prior career, and again mostly related to hard contact. 

Gallen is a pitcher of habit, and was usually exceptional in a more comfortable environment at home. And even in a season that saw some rough outings, his K/9 was well above 9.00, and he rarely walked batters.

A little more control on the fastball and some work on his sequencing could do wonders for the right-hander. Add all of that onto the fact that his BABIP was over .300 in 2023, and projections of a worse 2024 seem even less likely. 

With a full off-season to reload, and a fiery competitiveness to not be satisfied with a sub-standard 2023, Gallen will be a candidate for another ace-caliber season in 2024, and while he might not serve up the 2.54 ERA of his 2022 year, he'll likely do better than expected, and there's no reason to believe a pitcher with back-to-back near five-WAR seasons would drop almost a full win and a half.

2: RHP Paul Sewald

Projection: 60 IP, 3.75 ERA, 8.7% walk, 27.9% strikeout, 0.6 aWAR.

Sewald was a necessary addition, and a crucial part of the D-backs postseason push and playoff run.

Most will get hung up on the fact that Sewald's ERA with Arizona (3.57) was higher than his ERA with Seattle (2.93). But the season as a whole told a different story. He pitched in 39 save opportunities, more than his previous career total. As with many of the D-backs' arms in 2023, overuse led to some control issues, which led to rougher outings. He still got the job done 13 out of 15 times in the regular season, and six of seven times in the postseason.

Sewald's expected stats blew away his actual numbers. a 3.12 ERA translating to a 2.75 xERA, and a .189 xBA which ranked in the top 3% of MLB. 

Sewald's transition phase to Arizona didn't do him any favors, as he sat without needing to close a game in the middle of the D-backs' slump for eight days. His worst statistical month came in August, a month where he was asked to close nine games over a span of less than two weeks.

Not to say a closer shouldn't be able to pitch at any time, but a team would hope to not need to rely on their closer to come away with the win in every single game. Especially considering Arizona's bullpen still looked a little shaky, Sewald was the only thing stopping Arizona from another multitude of losses.

Outside of a low ground ball rate and a slight walk problem, his underlying metrics were all well above average in 2023, five of which topped out in the top 10% of MLB, and there wasn't a real sign of a decline in play outside of a rough month of August.

Sewald's ability to pitch well in high leverage (.204 average against in that split), and work through some outings that might look worse because of some walks or low xBA base hits suggest getting into a rhythm--and hopefully pitching a little less frequently--could easily see him outperform a near-4.00 ERA and a strikeout rate that was lower than what's been the norm. 

3: RHP Miguel Castro

Projection: 46.0 IP, 4.10 ERA, 10.2% walk, 23.9% strikeout, 0.2 aWAR.

Alright, hear me out.

Castro was certainly an unstable arm last season, and the main contributor of more than one loss. But his raw stuff is excellent. Outside of a walk problem stemming from some control issues, he didn't even get hit hard in 2023, with a 97th percentile hard-hit rate.

He also had a better xERA and xBA than both of his actual numbers, and limited solid contact for the majority of his season. So what is the real issue with Castro?

As previously mentioned, the D-backs asked a lot of their bullpen arms, especially in the first half of the season. Castro was called upon to be an occasional clean-up reliever, setup man and closer, and that could all fluctuate throughout the week.

Once the back end of the bullpen took form later in August, Castro was significantly better, pitching a scoreless September, through a 12 2/3 inning streak. So what changed? 

He stopped being a high-leverage reliever. 

His splits in 2023 showed a .291/.350/.564 slash in high leverage, and a .278/.350/.514 slash with RISP. However, in low leverage, he allowed a .170/.261/.255 slash, and a .173/.266/.268 with bases empty. 

Since the higher leverage relief roles are solidified, and the escape artist types like Ryan Thompson, Kevin Ginkel and Paul Sewald--who excel at stranding base runners--will be taking the majority of the reps Castro would have gotten early in 2023, Castro has a unique opportunity to pitch in his best possible form more frequently.

Considering how well he can lock down a middle inning, or be a bridge/cleanup role arm, his lowered workload and reduced role make him a sneaky candidate to have an excellent season, pitching in the environment he needs to excel. An ERA north of 4.00 is easily surpassable by the flame-throwing righty.

Summary

The D-backs' pitching staff has certainly come around as a whole. Guys performed at their best when needed, while others underperformed. The bullpen should be a much different unit with a full season of defined roles, and the starting rotation should--barring injury--also allow for more flexibility.

These three are the pitchers whose projections might sell them the shortest, but have a higher ceiling than what the shallow numbers will say.