Can Mason Black Be a Royals Success Story?

[Kevin O'Brien]

Image courtesy of © Dennis Lee-Imagn Images

 

On Tuesday afternoon, the Royals announced on Bluesky that they would be acquiring right-handed pitcher Mason Black from the San Francisco Giants in exchange for right-handed pitcher Logan Martin.

 

 

The move comes in the wake of the Giants designating Black for assignment on November 6th to make room for outfielder Justin Dean (formerly of the Dodgers) and left-handed pitcher Reiver Sanmartin (formerly of the Reds). Before Black could be a free agent, the Royals were able to pull off a trade for the talented but inconsistent righty.

 

 

The move now puts the Royals' 40-man roster at 37, according to Roster Resource as of November 11th. They have three open roster spots, but more should open up this offseason. Kansas City GM JJ Picollo will likely non-tender more players before the November 21st Non-Tender deadline, with some candidates being Jonathan India and Bailey Falter, who are estimated to command $7.4 million and $3.3 million this offseason, respectively. The acquisition of Black gives the Royals some flexible pitching depth, especially with Black still holding a Minor League option for 2026.

In return, the Giants receive Logan Martin, who posted a 3.45 ERA, 1.20 WHIP, and 11.1% K-BB% in 22 starts and 91.1 IP for the High-A Quad Cities River Bandits. Martin has pitched in the Arizona Fall League with Surprise, but has struggled with the Saguaros, posting a 9.82 ERA and 2.18 WHIP. Based on his pitching summary data from TJ Stats (utilizing his October 25th outing as an example), the former Kentucky Wildcat has shown good stuff, but struggled to generate chases and whiffs in Arizona.  

 

Even though it's not an "earth-shattering" move, Black is an intriguing arm with long-term potential who was once a top prospect in the San Francisco Giants system. Thus, can Brian Sweeney and the Royals' pitching coaches (sans Zach Bove, who is now with the White Sox) help tap into Black's full potential in Kansas City in 2026?

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A Look at Black's Time in San Francisco

Hopes were certainly high among Giants fans for Black, a third-round pick in the 2021 MLB Draft out of Lehigh University, a Patriot League school. 

Black had an excellent Minor League season in 2023, posting a 3.71 ERA, 1.21 WHIP, and 20.1% K-BB% in 29 starts and 123.2 IP between Double-A and Triple-A. As a result, MLB Pipeline ranked Black the Giants' No. 8 prospect entering the 2024 season. Here's what Pipeline said in their scouting report.

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Black is a sinker/slider starter who relies on his two main pitches about 90 percent of the time. His fastball sits at 92-94 mph and tops out at 97, though he has reached 100 mph in shorter stints in the past. His slider parks at 82-85 mph with sweeping action and he'll occasionally turn it into a harder, tighter cutter. 

Though Black's sinking changeup gets too firm in the upper-80s and he doesn't trust it, he actually has had more success against lefties than righties in pro ball. He creates deception with the extension in his delivery and has thrown more strikes as a pro than he did in college. He has the highest floor among San Francisco's right-handed pitching prospects and projects as a durable No. 4 starter. 

 

The combination of Black's diverse repertoire, solid command, and atypical delivery made him one of the Giants' better pitching prospects in the upper Minors, as seen below in this highlight film of him pitching with the Sacramento Rivercats, the Giants' Triple-A affiliate, in 2024.

Black finally made his MLB debut in May of that season, but the results weren't great in his initial exposure to Major League hitters. 

In nine outings (eight starts) and 36.1 IP with the Giants that season, the right-hander posted a 6.44 ERA, 1.68 WHIP, and 9.5% K-BB%. His FIP was only nominally better at 5.45, and his -0.2 fWAR illustrated how mediocre his San Francisco debut was a couple of seasons ago. While Black did flash some strikeout stuff, he didn't generate enough whiffs and chases, and he also struggled with giving up a lot of hard hits and barrels.

When looking at his TJ Stats season pitching summary profile, Black showcased slightly below-average stuff, with a 97 overall TJ Stuff+. As a result, he struggled to generate consistent chases (27.4%) and whiffs (16.4%), and he also gave up a lot of hard and productive contact, as illustrated by his .428 xwOBACON. 

His four-seamer was perhaps his most intriguing pitch in 2024, which he threw 31.5% of the time (his most used offering). Even though it sported a 95 Tj Stuff+ and 46 grade, he did produce a 30.6% chase rate and 23.1% whiff rate on the pitch, both above-average marks. The only problem was that he gave up a xwOBACON of .601 on the fastball, the worst mark in his six-pitch repertoire.

Things didn't seem to get better for Black in 2025. His ERA in Sacramento ballooned to 5.81 in 119.1 IP, and his 21.5% K rate was 2.2% lower than his Triple-A mark in 2024 and 6.4% lower than his mark with the Rivercats in 2023. His TJ Stats pitcher summary profile from Sacramento last year didn't look hot either, on both the stuff and results ends.

With the Rivercats last season, his overall TJ Stuff+ was 96, and he only posted a chase rate of 25.4%, a whiff rate of 24.8%, and an xwOBACON of .365. The latter two marks are around average to slightly below, but considering it was his third stint in Triple-A, he was expected to produce more dominant results.

Black only made one appearance in 2025 with the Giants, a four-inning relief appearance on the Fourth of July against the Athletics. He gave up five runs on five hits, including two home runs. However, he struck out five, walked zero, flooded the strike zone (71.6% strike rate; 55.4% zone rate), and showcased some intriguing development with his pitches from 2024, especially with the sweeper.

Against the A's, Black's sweeper sported a 103 TJ Stuff+ and produced a 47.8% zone rate and 41.7% chase rate. The 30.8% whiff rate and .373 xwOBACON weren't impressive, but were still serviceable, especially for a pitch that he threw 31.1% of the time.  In addition, he showed growth with his sweeper in nearly every category from the previous season with the Giants. He saw a `13.5% increase in chase, 14.8% increase in whiff, and a 59-point decrease in xwOBACON.

It's a small sample (one game after all). However, it showed that Black made the necessary adjustments to his pitch mix and quality, leading to improvement from his rookie season.

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Why the Royals Would Want Black

The one thing that sticks out about Black's history is that he is not just a student of the game, but an intelligent individual in general. Not only did he attend college at Lehigh, a pretty intense academic university, but he was also on the verge of entering medical school before getting drafted. 

Black's story and scientific approach to pitching were profiled in a short video segment from the San Francisco Giants back in 2023, when he was still a prospect in the Giants' farm system.

 

The Royals have seemed to thrive with pitchers who not only study their craft but are willing to make the necessary adjustments to their pitch grips and repertoires.

Seth Lugo finished second in the AL Cy Young race in 2024 thanks to the changes he made with the Royals. Cole Ragans went from questionable arm in Texas to Opening Day ace for the Royals. Lastly, Kris Bubic has thrived the most under Sweeney and the Royals' pitching development team, going from a mediocre starter to an AL All-Star last season.

Black certainly has the mindset to rebound in Kansas City, and his tools aren't bad, if they can be adequately developed. Last year, his 6'8 average extension ranked in the 80th percentile. It was 6'7 this year (yes, get your laughs in, Gen Z folks), but that still ranked above average. That extension can make up for the lackluster velocity, which Black sported last year (92.7 MPH fastball velocity). 

An example? Bubic, who utilized his 85th percentile (6'9) extension to produce a 76th percentile whiff rate (28.8%), despite an 18th percentile fastball velocity (92.1 MPH). Bubic also had an average arm angle of 38 degrees, not tremendously different from the 29-degree arm angle that Black showcased last season with the Giants.

Thus, it's in the realm of possibility that a few minor tweaks from Sweeney and the Royals' pitching coaches could help Black solidify the bottom of the Royals' rotation. If he doesn't have the length to be a starter, Black could thrive in the bullpen, especially with a four-seamer and sweeper combo that can be effective when utilized properly. 

That was on display in this strikeout of A's catcher Shea Langeliers in Black's lone outing last season.

 

Now, is Black going to be the next Bubic? That may be a little rash, especially since Black has proven far less at the MLB level than the former Stanford product. 

At the same time, Royals fans shouldn't sleep on or completely dismiss Black and his potential. He has the intelligence, the tools, and the repertoire to become a serviceable starter or reliever for the Royals as soon as next season. Furthermore, there is some long-term upside with Black if everything clicks in Kansas City, especially since he will be only 26 when pitchers and catchers report in February. 

 

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[Hokius]

I was always a Bubic believer and people kept telling me I was crazy. But I loved his approach to the craft. If Black has a little of that, I think he can thrive with this coaching staff. 

[Kevin O'Brien]

11 hours ago, Hokius said:

I was always a Bubic believer and people kept telling me I was crazy. But I loved his approach to the craft. If Black has a little of that, I think he can thrive with this coaching staff. 

Yeah, I think there's some potential there. He's got the intelligence and work ethic like Bubic, it seems, and I think he will mesh with this coaching staff. I'm not sure if he will be a starter or reliever, but I could see him take a step forward in development in Kansas City. 

[Lopsided]

Bubic was a favorite of mine since he came up. He reminds me of someone who looks like he should be a cakewalk to hit against, but he is really crafty. I like Bubic's makeup and I hope we get a chance to see him start in KC again this year.  I think Ragans, Lugo, Wacha, Bubic and Cameron put us on the right course.  I wonder how many teams in the past had a starting rotation with more lefties than righties.

[Kevin O'Brien]

14 hours ago, Lopsided said:

Bubic was a favorite of mine since he came up. He reminds me of someone who looks like he should be a cakewalk to hit against, but he is really crafty. I like Bubic's makeup and I hope we get a chance to see him start in KC again this year.  I think Ragans, Lugo, Wacha, Bubic and Cameron put us on the right course.  I wonder how many teams in the past had a starting rotation with more lefties than righties.

I like Bubic a lot too. That makeup and ability to modify and adapt quickly isn't easy to do. I think if he's healthy, he could be a key part of a playoff rotation in 2026. I guess the big thing is whether or not the Royals can sign him beyond this year. That's why I think the Royals acquired Black, to give them some depth both in the short and long term, especially if Bubic is traded or leaves.