I looked at Royals starting pitchers in my last post on Royals Steamer projections for the 2025 seasons. Even though there is some drop-off with the loss of Brady Singer, there’s enough depth in the system to possibly make up for Singer’s departure, especially if Kris Bubic returns to starting (which sounds like the case).
In the second part of this “2025 Royals Steamer Projections” series, I will examine the Royals’ bullpen, which was somewhat mixed in 2024.
In the first half, the Royals bullpen ranked 21st in ERA (4.21), 22nd in fWAR (1.2), and 29th in K% (19%). Their performance significantly improved after the All-Star Break, especially after Lucas Erceg joined the Royals from Oakland at the Trade Deadline.
In the second half, Kansas City ranked 16th in ERA (4.00), 11th in fWAR (2.3), and 19th in K% (23.6%). After struggling before the All-Star Break with James McArthur, Will Smith, and Chris Stratton, Erceg, Bubic, Angel Zerpa, and Daniel Lynch IV led the way, making the Royals one of the best relief units in the last month of the season.
According to Fangraphs, the Royals bullpen ranked 4th in fWAR (1.8), ERA (2.77), and K% (29.4%). Thus, it’s unsurprising that the bullpen locked down a series victory against the Orioles in the AL Wild Card round in Baltimore.
Therefore, what should Royals fans expect from this group in 2025, especially with the return of Hunter Harvey, who didn’t pitch much after being acquired by the Nationals due to an arm injury?
Here are the 2025 Royals reliever Steamer Projections and three takeaways regarding the data set for the upcoming season.
Royals Relief Pitcher Projections for 2025
The categories are similar to the starting pitcher projections I shared in my last post. The main difference is that I eliminated quality starts, games started, and losses and added saves and holds in their place. I decided to keep losses out of this sample mainly because the numbers were so low, which makes sense for relievers with more limited pitching samples.
Here’s the link to the spreadsheet I compiled and organized using the Fangraphs data. In addition to having the sheets embedded in the respective posts, I also have a list of pitching prospects for whom there were Steamer projections. Still, I was uncomfortable analyzing them due to their limited sample size.
Also, I didn’t include Alec Marsh, Noah Cameron, or Bubic in this analysis, primarily because I analyzed them as starting pitchers. I believe that will be their role in Spring Training.
Erceg and Harvey Should Carry the Royals Bullpen
Regarding fWAR, Steamer is projecting Erceg and Harvey to carry the Royals bullpen in 2025.
The 29-year-old former Athletics reliever has the best overall outlook of any Royals reliever in this set of Steamer projections.
Steamer expects Erceg to produce a 3.42 ERA, 3.38 FIP, a 27.1% K rate, a 17.9% K-BB%, and a 44.8% GB rate in 67 appearances and innings. Steamer also projects for Erceg to lead the Royals in saves with 29 and gain four wins. Thus, Erceg is projected to produce a 0.7 fWAR, tied for a team-high among Royals relievers.
The other reliever tied with Erceg with a 0.7 fWAR? None other than Harvey, which is a bit of a surprise considering he put up a 6.35 ERA, 6.34 FIP, 17.2% K%, 3.4% K-BB%, and -0.2 fWAR in six appearances and 5.2 IP with the Royals last season.
Steamer projects that Harvey will produce a 3.62 ERA, 3.44 FIP, 25.8% K%, 18.1% K-BB%, and 42.5% GB% in 62 outings in 2025. The former National’s ERA is higher than Erceg’s, but Harvey’s K-BB% is slightly better, and his walk rate is 1.5% lower than the projected Royals closer. Steamer projects Harvey to collect 14 holds and three wins, which is not bad for an 8th-inning setup man.
Royals fans who only saw Harvey in Kansas City may be hard-pressed to believe he can produce the numbers that Steamer is projecting for next season. However, he sported a 4.20 ERA, 3.17 FIP, 26.3% K%, 20% K-BB%, and 0.9 fWAR in 45 IP with the Nationals before the trade. Unfortunately, Harvey was never healthy when he arrived in Kansas City, and his four-seam monthly velocity data seems to back that up.
Harvey’s PLV pitch quality wasn’t as strong in 2024 as in 2023. Here’s a look at how his arsenals compared over the past two seasons via PLV metrics.
Harvey’s fastball got better in 2024, as did his splitter. Conversely, his curve and slider took a step back, as they both posted sub-five marks last season.
If Harvey is fully healthy in Spring Training, Brian Sweeney, Zach Bove, and bullpen coach Mitch Stetter will likely work with him to see if he can get the quality back on one (or both) of those breaking offerings in 2025.
If that breaking ball improvement and fastball velocity bounceback happen this spring for Harvey, Royals fans should expect the right-hander to live up to and maybe surpass his optimistic Steamer projections.
Sam Long and Chris Stratton Could Struggle
The left-handed Long was a non-roster invitee to Spring Training who had a stellar campaign with the Royals in 2024.
In 43 outings and 42.2 IP, the former Athletics and Giants pitcher produced a 3.16 ERA, 3.89 FIP, 25% K%, 15.3% K-BB%, 42.9% GB%, and 0.2 fWAR. All those metrics were career-best marks for the 29-year-old, and he ended up being a key reliever for the Royals down the stretch and even in the postseason.
The Steamer projections aren’t dire for Long, but they predict some significant regression from what he produced a season ago.
Steamer projects Long in 61 appearances to produce a 4.32 ERA, 4.36 FIP, 1.40 WHIP, 20.5% K%, 11.1% K-BB%, 39% GB%, and -0.1 fWAR. Long is one of four relievers projected to sport a negative fWAR in 2025, primarily due to his significant steps back in all the pitching categories from last year. Steamer does project Long to collect 12 holds, so they expect Long to be in the setup mix again next season.
I like Long a lot, but fellow lefties Angel Zerpa (3.67 ERA), Evan Sisk (3.99 ERA), and Lynch IV (4.25 ERA) have much rosier projections. Thus, Royals manager Matt Quatraro won’t be patient with the Sacramento State product.
Furthermore, Long has no Minor League options remaining, so he will need to come out on fire in 2025, much like he did in 2024. If that doesn’t happen, then his projection outlook may be a bit too optimistic, which means that Long may be on his way out of Kansas City sooner rather than later.
As for Stratton, he opted into his player option for 2025, which was to be expected after he produced one of the worst seasons of his career.
In 57 outings and 58.1 IP, the former Giants draft pick sported a 5.55 ERA, 4.62 FIP, 17.1% K%, 4.3% K-BB%, 44.9% GB%, and -0.2 fWAR. Stratton was better at inducing groundball contact, as his GB% was 6.3% higher than his mark in 2023 with the Rangers. However, his K% dropped by 6.9% and his BB% was 12.8%, a 5.4% increase from 2023. Thus, his lack of stuff and questionable pitch mix led to lackluster results.
That said, his PLV pitch quality wasn’t all that bad, beyond his four-seamer, an offering he threw 38% of the time last season.
Stratton had four ABOVE-average pitches on a PLV end last year. Unfortunately, his primary offering (four-seamer) was so poor that it weighed down his overall pitch arsenal’s effectiveness.
Steamer projects some improvement for Stratton in 2025.
In 57 appearances, Stratton is projected to produce a 4.57 ERA, 4.54 FIP, 18.9% K%, 9.2% K-BB%, 40.5% GB%, and -0.1 fWAR. It’s all better than what he did in 2024, but last season was such a low bar that these projected metrics aren’t even average (which his negative fWAR illustrates).
The Royals have higher-upside arms on the 40-man roster with better projections than Stratton, like Jonathan Bowlan (4.40 ERA; 0.3 fWAR) and even Steven Cruz (4.32 ERA; 0.0 fWAR). Therefore, this could be a critical Spring Training for Stratton to show that he can still have a spot in this Royals bullpen.
If he continues to struggle in Cactus League play, it wouldn’t be surprising for JJ Picollo to eat Stratton’s remaining $4.5 million to make room for a younger arm with more projection (and more extended team control).
James McArthur Bounce Back?
McArthur was a popular whipping boy for frustrated Royals fans last season. The critique was unfair: McArthur wasn’t projected to be the Royals’ closer in Spring Training, but an awful season from Will Smith thrust the former Phillies prospect into the role sooner than expected.
McArthur was a weird case statistically for the Royals in 2024.
On the one hand, the numbers were terrible. While he saved 18 games in 57 appearances, he had a 4.92 ERA, 1.45 WHIP, 19.8% K%, 14.2% K-BB%, and 0.1 fWAR. That’s not good enough for a medium-leverage reliever, let alone one getting multiple opportunities in high-leverage situations.
Hard hits and the long ball were massive issues for McArthur last year.
His 8.3% barrel rate allowed was nearly double his mark in 2023 (4.7%), and his 16.7% HR/FB rate was 4.5% higher than his rookie season rate. McArthur ran into rough batted-ball luck last year (.347 BABIP, nearly 50 points higher than in 2023). That said, his lack of ability to put hitters away with strikeouts was why he couldn’t hold onto the closer’s job a year ago.
When looking at his PLV metrics, though, McArthur sports a good foundation as a reliever.
McArthur’s slider and four-seamer rated poorly on a PLV end last year. However, his sinker was a very good pitch, and his curve was elite. If McArthur can clean things up with his slider and four-seamer, he could become a solid middle reliever for the Royals in 2025.
Steamer also projects that he can be that dependable middle-innings pitcher for the Royals.
In 48 outings, he is projected to produce a 3.92 ERA, 3.85 FIP, 21.1% K%, 13.7% K-BB%, 46.9% GB%, and 0.3 fWAR. Only Erceg, Harvey, and Zerpa are expected to produce better FIP marks than McArthur in the Royals bullpen.
Thus, I don’t think Royals fans should sleep on McArthur, who will come to spring camp in Surprise with much less pressure than a season ago. With a more apparent middle-innings relief role (and a Minor League option remaining), McArthur can make the necessary adjustments on his slider and four-seamer in Spring Training or even at the start of the year in Omaha if they are not quite where they need to be quality-wise.
A slower development process for McArthur could help the 27-year-old get back to where he was at the end of 2023, where he looked like he could be a key reliever for Kansas City for quite some time.
Steamer projects that he can return to those levels in some capacity in 2025. Now, we need Royals fans to believe it as well.
Photo Credit: Peter Aiken Imagn Images
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