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# Analysis: Mariners Bolster Bullpen by Acquiring Caleb Ferguson From Pirates
- URL: https://www.emeraldcityspectrum.com/analysis-mariners-bolster-bullpen-by-acquiring-caleb-ferguson-from-pirates/
- Published: 2025-07-31T01:33:55.000Z
- Updated: 2026-10-08T05:37:00.000Z
- Author: Corbin Smith
- Tags: Analysis, Mariners, Caleb Ferguson, MLB Trade Deadline

\[caption id="" align="alignnone" width="1080"\]

![  Pittsburgh Pirates left-handed pitcher Caleb Ferguson fires a pitch during a regular season game. The Mariners acquired Ferguson via trade on July 30. Credit: Caleb Ferguson/Instagram  ](https://storage.ghost.io/c/1d/f2/1df2f77b-83dd-4bc0-a6d2-6d1bb5df89a3/content/images/2026/10/501586362_18501907183052925_8989346160111826980_n-format-original.jpg)

Pittsburgh Pirates left-handed pitcher Caleb Ferguson fires a pitch during a regular season game. The Mariners acquired Ferguson via trade on July 30\. Credit: Caleb Ferguson/Instagram \[/caption\]

The Seattle Mariners made their second trade of the deadline season Tuesday, acquiring left-hander Caleb Ferguson from the Pittsburgh Pirates in exchange for right-handed pitching prospect Jeter Martinez. 

Like we did when Seattle acquired Josh Naylor from the Diamondbacks, I will ask myself easy questions to explain how Ferguson can help, what could potentially be worrisome, and what they gave up in order to acquire the southpaw for the rest of 2025.

### Who is Caleb Ferguson?

Fair question. Ferguson is a left-hander who has been around for a while. He has been a regular member of a bullpen since the 2018 season. He spent his first five seasons with the Dodgers and was able to forge a 3.43 ERA with a 247/82 K/BB over his 201 innings. He was traded from Los Angeles to the New York Yankees before the 2024 season, and it didn’t go particularly well with a 5.13 ERA before being dealt to Houston just before last year’s deadline. He did a solid job with the Astros, and then signed a one-year, $3 million contract with the Pirates prior to the 2025 campaign.

In his one year with Pittsburgh, Ferguson has registered a 3.74 ERA, 34/14 K/BB and 1.09 WHIP over 43 1/3 innings across 45 appearances.

### What does Ferguson do well?

Ferguson is very difficult to square up. Very difficult is a tremendous understatement. His hard-hit percentage allowed of 25.3 percent is among the very best in baseball, as his the average exit velocity allowed of 83.5 mph. He generates ground balls 51.2 percent of the time, and he’s almost impossible to barrel as seen in a percentage allowed of 3.3 percent. 

The key for Ferguson is the ability to generate plenty of movement on his pitches, but in particular his sinker. He’s allowed hard hits on that pitch just four percent of the time, a borderline unrealistic number. He also offers deception on his delivery as seen in a chase rate of 30.2 percent. 

### Is He Better Against Lefties Than Righties?

Yes, but he’s not bad against righties. He’s straight-up death to southpaws, however. They’re hitting just .167 with a .439 OPS against Ferguson in 74 plate appearances. Those numbers jump up to .250 and .690 against right-handers, but those are obviously solid numbers as well. 

So yes, better. But he’s far from a liability when facing hitters from the opposite side of the plate.

### What Does Ferguson Struggle With?

Ferguson has been a guy who has missed bats for the overwhelming majority of his career, but that hasn’t been the case in 2025\. He’s generating just a 19.3 percent strikeout rate in 2025, which puts him in the 29th percentile of qualified pitchers, but he’s been much worse than that in terms of generating whiffs. Hitters are swinging and missing at Ferguson’s arsenal just 18.5 percent of the time, which is in the bottom seventh percentile.

When you generate as much weak contact as he does, that matters less, but Ferguson will need a steady defense behind him, particularly in the infield.

### What Did Seattle Give Up?

With all due respect to Jeter Martinez -- a terrific baseball name -- not a lot. Martinez has an ERA over 6 with Low-A Modesto, and while he touches triple digits with his heater and has shown a quality slider -- and it’s worth pointing out he doesn’t turn 20 until February -- there’s a lot of doubt as to whether nor not he’ll have the command to become more than organizational depth. It’s not a bad get for Pittsburgh to have a lottery ticket for a player that served no purpose to the Bucs for the remainder of 2025, but this is a pretty easy yes for Seattle.

### Is The Bullpen Set?

I think so. It wouldn’t stun me if they got one more bullpen arm before the deadline, but a group of Andres Munoz, Matt Brash, Eduard Bazardo, Gabe Speier, and Ferguson -- among others -- should be good enough. Maybe this isn’t the most dominant bullpen in baseball because it isn’t, but it’s more asset than detriment now, and that’s good for a team that still needs to win games with run prevention.

There’ll definitely be more exciting trades and hopefully the Mariners are among the teams who make one of them before Thursday, but they got better without giving up much. Good stuff.