Is there any hope for Marlins' highest-paid reliever in 2025?

[Ely Sussman]

Woo-Suk Go flunked his first season in the United States, but with the Marlins on the hook for his 2025 salary, they've invited him to spring training hoping to extract some kind of value out of him.

Just four months after inking South Korean right-hander Woo-Suk Go to a two-year, $4.5 million deal, the San Diego Padres were ready to cut their losses. Go was part of the package that the Miami Marlins received in exchange for Luis Arraez last May, but he wasn't an asset in the trade—the Marlins took on the remainder of his contract as a favor, enticing the Padres to part with better prospects than they would have otherwise (Dillon Head, Jakob Marsee and Nathan Martorella).

Following the trade, Go continued to underwhelm in the upper minors. After only seven relief appearances as a member of the Marlins organization, he was designated for assignment to create space on their 40-man roster. The Marlins would shatter their single-season franchise record by using 45 different pitchers in 2024, but he wasn't one of them.

Even so, the Marlins haven't entirely given up on Go yet. They owe him a $2.25 million salary in 2025 regardless, which is more than any reliever who's actually on Miami's roster. Before flushing that money down the drain, he's been given the opportunity to make another impression during spring training as a non-roster invitee to big league camp.

Go had seven seasons of professional experience in the Korea Baseball Organization before signing with the Padres, peaking as one of the league's best closers. And yet, he's still just 26 years old, younger than many of his fellow Marlins NRIs. Perhaps the team wouldn't be as patient with a comparable player who was already in his 30s. 

Coming over from the KBO, Go's fastball velocity was believed to be "sitting 93-95 mph, up to 98," according to a scouting report from Eric Longenhagen of FanGraphs. We didn't see that in stateside competition. His four-seam fastball only averaged 92.8 mph during Triple-A appearances, peaking at 95.7. It also had a relatively low spin rate of 2,120 rpm, which would have ranked around the 13th percentile of qualified MLB four-seamers last season, per Baseball Savant. With that pitch as his primary weapon, he struggled to induce swings-and-misses.

The table below is courtesy of Thomas Nestico's pitching summary app.

Go was victimized by ineffective defense in 2024. He posted a 6.54 ERA, but a substantially lower 4.87 FIP. It's reasonable to expect his .370 batting average on balls in play to improve even if he pitched in front of the same group of fielders moving forward.

That being said, a turnaround in luck would only take Go so far. The quality of the swings taken against him may also be an indication that he was too predictable.

Opponents loved ambushing Go on the first pitch of a plate appearance. When putting those pitches in play, they slashed .480/.500/1.040 with eight extra-base hits. Here's new teammate Eric Wagaman clobbering a belt-high fastball for a 422-foot home run.

Runners went 12-for-14 when attempting to steal bases against Go (an incredible throw by Will Banfield prevented them from going 13-for-14). It's not uncommon for relievers to be neglectful of men on base, but unless the quality of Go's stuff ticks up, he has little margin for error. He'll be allowing a lot of balls in play if ever summoned to the majors and those become more damaging when you're nonchalant about letting guys advance into scoring position.

Inviting Woo-Suk Go to big league camp is understandable when the Marlins truly have nothing to lose. However, after closely reviewing his previous campaign, I didn't come away with much reason to be optimistic. He doesn't have any sort of background as a starter and only topped out at two innings in his longest outings, making him an awkward fit even for mop-up duty.

The 2024 Marlins received solid bullpen production from some unexpected sources. Let's see if that trend continues into 2025 with Go.

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[Hans Herrera]

Smells like Sixto all over. 

[BMK3]

Actually the Marlins do not have a terrible bullpen although they do lack big names.  Things will have to break well but Faucher was pretty good and did well as a closer.  I like Nardi and Bender can be good ( if he ever figures out that it is OK to throw a strike on 0-2). Cronin, Curry, Veneziano, Tinoco all may have gotten some confidence that they can do it. I think Meyer will find a prominent place there.  Go-Suk Wood had something that attracted scouts. Let's see if he can find it again.

[DevinD]

So, I know he’s a long shot to make the team but I just think he should rely a bit more on his off speed pitches like his Curveball that has a 100 tjStuff+ rating. He should also maybe try to develop a changeup to keep hitters off of his below average fastball. He doesn’t really a lot of vertical ride to his fastball so the only Go can be successful, in my opinion, is to change speeds and use his fastball less frequently. 

[rurrusuno]

If we're paying him a couple million, then might as well give him another shot. I just don't expect much to come out of him. 

[One Regend]

To be honest, I have no idea what the Padres saw from Woo-Suk Go when they scouted him. Even if he was the next Francisco Rodriguez, you don't throw around $2.25 million AAV to a strictly bullpen guy who has yet to even prove he could get major league hitters out. That kind of mistake should get A.J. Preller fired, but this trade may very well have saved his job.

[Brock Beauchamp]

On 1/31/2025 at 2:25 PM, DevinD said:

So, I know he’s a long shot to make the team but I just think he should rely a bit more on his off speed pitches like his Curveball that has a 100 tjStuff+ rating. He should also maybe try to develop a changeup to keep hitters off of his below average fastball. He doesn’t really a lot of vertical ride to his fastball so the only Go can be successful, in my opinion, is to change speeds and use his fastball less frequently. 

Sorry for the delay in approving this post!

[1993 fan from start]

On 1/31/2025 at 7:51 AM, Hans Herrera said:

Smells like Sixto all over. 

SO  Woo-Suk Go injure prone like Sixto ?  

[1993 fan from start]

this be one of the first test throwing traner Daniel Moskos have .   from my stand point he going to have to locate the ball more  and set up his curveball to be use more.  if  their a  drop off in spinrat and mph.   or work keeping the into the park more fly rate   Just hoping marlins get more out of him. If not big  improvment .    it may take to end of spring for we see that.  depend on his offseason workout.