Five free agent suggestions to help elevate the Mariners' bullpen
Seattle's bullpen was great last year. But adding an established arm to this talented group would be a prudent move.
During the most recent Seattle Sports Radio Hot Stove podcast, Mariners GM Justin Hollander suggested to hosts Aaron Goldsmith, Gary Hill Jr., and Shannon Drayer that his team would like to augment the bullpen. More specifically, a reliever capable of pitching late in games.
“If we could add something to the bullpen to continue to take the pressure off (Matt) Brash and ‘Muni’ (Andrés Muñoz) and (Justin) Topa and (Gabe) Speier at the very back end of the game, that would be appealing to us.” - Justin Hollander
Whether this means the Mariners target a high-profile name or someone unheralded like a Matt Brash, Andrés Muñoz, Justin Topa, Gabe Speier, or Paul Sewald is unclear. But with Spring Training just a month away, let’s consider free agent candidates capable of satisfying Hollander’s description.
Just to be clear, I chose to avoid including the shiniest stars on the market on my list. Perhaps the Mariners go after a premium reliever. But for a variety of reasons, I suspect the team goes in a different direction. Therefore, I identified five lower-profile, but recognizable, quality arms with late-inning experience.
Note: Unless otherwise noted, rankings are a comparison of the player being discussed to the 222 pitchers who faced at least 150 hitters as a reliever last year.
Phil Maton
Selling points: Maton did a great job of minimizing hard contact in 2023. The right-hander limited opponents to a 23.5-percent hard-hit rate, which was second-lowest among relievers. Only Tommy Kahnle of the Yankees (22.7-percent) was better.
Last season with Houston, about two-thirds of the 30-year-old Maton’s 66 innings were logged during the sixth or seventh inning.
By virtue of being a former Astro, Maton has experience with playing meaningful October baseball. In 21.2 postseason innings with Cleveland and Houston, the Louisiana Tech product held opposing hitters to a .149 AVG, while striking out 22 and walking five.
Potential concerns: It’s worth noting opponents did boast a .815 OPS against Maton in the second half of 2023 compared to a .541 OPS prior to the All-Star break. This may be attributable to an elbow injury sidelining the Kentucky native for just over two weeks in August. Still, Maton did manage to hold opponents to a .525 OPS in 18 regular season and playoff appearances following his return from the IL.
Matt Moore
Moore spent most of last year with the Angels. However, he was one of several veterans waived by the team in August as part of a reported effort to get Anaheim’s payroll below the Competitive Balance Tax threshold. Cleveland claimed the 34-year-old, but would waive him several weeks later. Moore’s final destination in 2023 was Miami for the last week of the season.
Selling points: About 87-percent of Moore’s workload transpired during innings seven through nine. He was primarily a one-inning reliever, although the left-hander registered four-plus outs on eight occasions, including a pair of two-inning stints with the Halos early last season. It’s worth noting he made 14 two-inning relief appearances with the Rangers in 2022. Could returning to a multi-inning role in 2024 be a possibility?
Hitter handedness hasn’t been an issue for Moore. Over the past two seasons, he’s held right-handed hitters to a .255 wOBA. This was best among 65 southpaw relievers facing at least 100 righty bats in 2022-23.
Weighted On-Base Average (wOBA) is a sabermetric version of on-base percentage (OBP) that credits hitters for how he reached rather than treating all on-base events as equals, as OBP does. For instance, a double is more valuable to run production than a single, a home run more than a double, etc. MLB league-average wOBA last year = .312
Potential concerns: Moore did miss 48 days in the first half of the 2023 campaign due to an oblique strain. Might this injury torpedo my suggestion of a return to being a multi-inning weapon?
Perhaps. But it’s important to note Moore remained fully available in 2022, although a back issue did sideline the eighth round pick of the 2007 Devil Rays twice in the season prior.
David Robertson
Selling points: Easily the oldest candidate on our list, Robertson will be entering his age-39 season. But despite being a graybeard for a baseball player, he’s continued to be an effective reliever.
In 2022-23, the right-handed Robertson served as a late-inning weapon with the Cubs, Phillies, Mets, and Marlins. All told, he appeared in 120 games holding 533 opposing hitters to a .198 AVG with 38 saves.
In Robertson’s case, age also comes with postseason experience. The 17th round pick of the Yankees has appeared in 42 playoff games. Only three active pitchers have more: Kenley Jansen (59), Ryan Pressly (46), and Aroldis Chapman (44). A player who knows what it takes to reach and succeed in the postseason provides an intangible value to a contender.
Potential concerns: The Marlins acquired Robertson prior to the 2023 trade deadline to close games. But ineffectiveness prompted his removal from the closer role in late-August. That said, the Alabama alum pitched very well in the sixth through eighth innings during September.
Robert Stephenson
Selling points: Stephenson began the year with the Pirates and wasn’t particularly effective. But once joining the Rays via an early-June trade, the right-hander was extremely impressive for the remainder of the 2023 campaign.
Creating swings and misses was Stephenson’s specialty. His 46.3-percent whiff rate was tops among 422 starters and relievers inducing at least 300 swings. Furthermore, only two relievers - Félix Bautista (46.4-percent) and Aroldis Chapman (41.4-percent) had a higher strikeout rate than the 27th overall pick of the 2011 draft.
If Stephenson had been a Mariner in 2023, he would’ve ranked first among Seattle relievers in strikeout rate, AVG, OBP, and wOBA. Only Sewald produced a better xwOBA (.216) than the 30-year-old.
Potential concerns: Stephenson missed the first two weeks of the 2023 campaign after experiencing elbow inflammation in Spring Training. The Californian didn’t lose time in 2022 due to injury, but did have the misfortune of contracting COVID-19 twice. That said, back issues cost Stephenson a combined two months in 2020-21.
Keynan Middleton
Selling points: Like Stephenson, Middleton was adept at missing bats last year. The former Mariner’s 36.1-percent whiff rate was 16th-best in the group of 422 hurlers just mentioned. Furthermore, his 30.2-percent strikeout rate was a career high and nearly five-percent better than the previous best he set as a rookie with the Angels in 2017.
All but 10 of Middleton’s 50.2 innings were logged in the seventh frame and beyond. It’s also worth noting the Halos’ third round pick in 2013 made eight multi-inning relief appearances last year. This includes a pair of two-inning outings for the Yankees after being traded to the Bronx by the White Sox in August.
Potential concerns: Perhaps this is nothing more than the randomness of baseball. But the righty walked 15.2-percent of right-handed batters last year. Conversely, he had a 4.6-percent walk rate versus left-handed opponents.
Shoulder inflammation cost Middleton the final month of the season with the exception of an appearance on September 29. The Oregon native also missed about two weeks in both 2021 and 2022 due to elbow and biceps issues.
Final thoughts
If given a choice, my order of preference would be Maton, Moore, Robertson, Stephenson, and Middleton. I like all of these pitchers; any could help Seattle’s bullpen this year. But I’m most attracted to Maton knack for minimizing damaging contact, plus his demonstrated ability to succeed on the biggest stage.
Naturally, there is risk associated with all of our candidates. Each has experienced arm-related health issues in recent years. Moreover, the term “reliever volatility” exists for a reason - regression happens. Still, all but Stephenson have strung together multiple strong campaigns recently.
Whether Seattle’s management would have interest in any of these relievers is unknown. The same applies with each player’s desire to be a Mariner in 2024. After all, free agents with value generally have multiple suitors, which means they have choices.
Still, adding one of the pitchers we’ve talked about or someone of this ilk seems like a logical move to this blogger.
The quartet of Muñoz, Brash, Topa, and Speier was phenomenal for the Mariners last year. But let’s not forget Seattle relievers were asked to do more last September when the rotation faltered. This additional workload, combined with the trade-induced absence of Sewald, didn’t set up the bullpen for success during the most critical month of the season.
No need to relieve that nightmare this coming September.
My Oh My…