The Mariners bullpen finished 17th in WAR across MLB last season. Consequently, bolstering the bullpen has been on Seattle’s to-do list this offseason. While I support investing in additional arms, I also believe the M’s have a breakout candidate already on their roster.
Carlos Vargas isn’t an unknown quantity, having finished second on the team in reliever innings and third in pitching appearances. He posted a solid 3.97 ERA over nearly 80 innings of work last season, though additional pitching metrics like FIP- didn’t view him as favorably, resulting in a -0.7 fWAR last season.
Still, I can’t help but watch Carlos Vargas and hope Dan Wilson has another high leverage arm in the waiting. As I will detail in this post, Vargas has great stuff. My hope is that changing up his pitch mix a bit and refining a surprise tertiary offering that’s already in his arsenal will allow him to make massive strides in 2026.
Superb Stuff:
Electricity is something that you have or you don’t. Carlos Vargas has it.
In 2025, the 26-year-old right-hander had a 115 Stuff+ grade across his pitch arsenal. For the sake of comparison, fan favorite Matt Brash has a 115 Stuff+ mark for his career. Also, while the Mariners’ elite closer Andres Munoz has a 123 Stuff+ score since entering MLB, he’s posted 115 and 114 over the past two seasons.
In short, Vargas is as “nasty” as two of the best relievers in the game. The tools are there to be harnessed and refined into a dynamic repertoire that opposing batsmen fear.
“Out Pitch” Identification:
Elite bullpen arms tend to have a go-to pitch to terminate plate appearances. Keeping it in the family, Andres Munoz has his slider, which he throws roughly 50(fifty!) percent of the time. Looking outside the organization, top-notch hurler Devon Williams also has a near dead-even split between his heater and his devastating changeup.
Another pitcher I looked at is Yennier Cano. During his 1.7 WAR 2023 campaign, the Orioles reliever threw his changeup 28% of the time. Why did I look at Cano as a comparison? I will get to that later.
Nevertheless, these bona fide bullpen arms have a refined, deadly “secondary” offering. At this point, it doesn’t seem that Carlos Vargas does.
That’s not to say he can’t find one, and quickly. As I mentioned above, he boasted a 115 Stuff+ last year. The following pitches individually posted marks above league average stuff (100 on Stuff+): four seam fastball, sinker, cutter, slider, changeup.
Purely from a velocity and movement standpoint, Vargas has plus offerings to choose from. With that said, I think it’s imperative that he narrows his arsenal to a few pitches that he can develop into weapons.
As of now, he relies on his sinker roughly 63% of the time. It’s a great pitch, don’t get me wrong, posting a run value of 7 on Fangraphs and an otherworldly 64.2% groundball rate. This should remain his primary offering.
None of his other pitches are thrown even 20% of the time. Also, it’s worth noting that none of those options posted a positive run value. This kicks off a chicken-egg debate. Does he not trust any of those pitches to be productive? Or would committing to one or two of those allow him to develop pitchability around these already “stuffy” secondaries? I would like to argue for the latter.
Bet on the Slider:
In 2025, Vargas’ primary non-sinker pitch was his slider, which he threw 19% of the time. His slider logged a -0.6 run value on FanGraphs, making it his second-most valuable option.
The 118 Stuff+ number that comes with it is evidence of the fact that it can be an effective pitch. This breaking ball generated a respectable 27% whiff rate according to Baseball Savant, the second-highest of his secondaries. Additionally, the 28% swing rate it generated on pitches out of the zone was best of his non-sinker pitches.
To me, this is a better option than his cutter, which he threw 13% of the time last year. His cutter notched a run value of -1.2 and tied for the lowest Stuff+ rating of all the pitches in his arsenal.
If Carlos decreases his reliance on the cutter and dedicates more time this offseason to turning his slider into a plus offering, it will help him miss more bats. Additionally, that pitch becoming more reliable will help him alleviate the heavy lifting done by his sinker, keeping hitters off balance more.
New Tertiary Offering:
In deep diving on Vargas’ numbers, I was intrigued by his changeup. He threw it just 21 times last year; however, it had the highest Stuff+ rating of any of his pitches at 120. Additionally, it generated the highest whiff rate, posting a 44% mark. Is there something to tap into here?
The risk of his change is when it was hit, it was HIT. In four batted ball events, he allowed three hits, including a double and home run. The good was great. The bad was damaging.
Nevertheless, I can’t help but wonder if this pitch is the stuffiest of his already quite stuffy arsenal and its proven that it can miss bats, that it could be the tool that unlocks Vargas’ development into a high-leverage arm. Frankly, his impressive groundball rate is nice, but raising his career K/9 from 6.72 is going to be pivotal for navigating out of jams or getting through the teeth of an opponent’s order in a tight game.
This brings me back to the Yennier Cano comparison. Both are 6’4 and are sinker-ballers. Cano in 2023 averaged 96.5 MPH on his fastballs, as did Vargas in 2025. Each also sit in the low-90s with their changeups. Sure, Cano’s delivery slot is much lower than Vargas’ but there’s enough there to dream on.
As mentioned above, if Vargas deprioritizes his cutter and lowers his sinker utilization into the mid 50% range, that will pave the way for him to solidify his changeup as his tertiary pitch, perhaps sitting somewhere between 11-14% in usage.
Committing to sharpening his slider and changeup would allow him to master the pitchability of those already nasty offerings. If he’s able to trust both to not only miss bats and generate swings on pitches out of the zone, but also locate them for strikes and throw them early in counts, he will be able to keep hitters off balance and spike his strikeout rate.
Is it unrealistic to see him jump from 21 total changes thrown across nearly 80 innings last year to suddenly relying on it as his third option? I don’t think so. All of his changeups were thrown August 14th or later, boasting a 8.5% usage rate from then until the end of the season.
I believe in Carlos Vargas. He has wicked stuff and still under 100 MLB innings under his belt. As he continues to develop the secondaries, he will ascend from a groundball generating contact manager to a devastating bat-misser that the Mariners can leverage in high innings.