Mariners Begin to Address Their Historically Bad Bullpen

After going all in on their rebuild in 2019, the Mariners have cycled through what seems like a million different pitchers in just two years. (The real figure is 61, the highest number of pitchers used by any team over the last two seasons.) That shouldn’t be surprising considering general manager Jerry Dipoto’s reputation for roster churn and the team’s goal of building a contender in just a few years time; scouring the waiver wire and the Mariners’ minor league system for pitchers who might show enough promise to stick around for a while requires a constant flow of transactions.

Finding plenty of lumps of coal in their quest to uncover those hidden gems, Seattle’s bullpen has been particularly bad as the team prepares to contend again. Over the last three decades, no relief corps has posted a league- and park-adjusted FIP worse than the 2020 Mariners, 33% below league average. They would have had the worst league- and park-adjusted ERA too if it weren’t for the 2020 Phillies’ atrocious bullpen and their 7.06 ERA. When we adjust their collective strikeout-to-walk ratio for their historical context, the 2020 Mariners had the fourth worst K/BB+ in that period, 37% worse than league average.

With their eyes set on coming out of their rebuild as early as next year — but more realistically in 2022 — Dipoto has made addressing that historically bad bullpen a primary goal of this offseason. The Mariners already re-signed Kendall Graveman, one of the few bright spots in the bullpen this year, and selected Will Vest in the Rule-5 draft last week. Yesterday, they took another next step in bolstering their bullpen by acquiring Rafael Montero from the Rangers. In return, 17-year-old prospect Jose Corniell and a Player To Be Named Later are headed to Texas.

Spending prospect capital to acquire a reliever when the free agent market is ripe with relief options is certainly an interesting choice for Seattle. They’ve been linked to Blake Treinen and a handful of other relievers this offseason and seem to have room to add payroll. Trading away a young international signee for some relief help is a move a team on the edge of contention makes to push them over the hump. Montero is already 30 years old and has just two years of team control left so he’s not likely to be around for the peak of the next competitive Mariners team. With top prospects Jarred Kelenic and Logan Gilbert likely to make their debuts mid-season next year, perhaps this is a signal the Mariners see an opportunity to take a step forward against their division foes.

For his part, Montero isn’t necessarily a bad pick up for Seattle. He peaked as the No. 5 prospect for the Mets back in 2013 and was lauded for his command of his fastball and solid secondary offerings. Things did not go well after making his major league debut in 2014 as his once sterling command eluded him in the majors and he dealt with a litany of injuries. A shoulder injury wiped out most of his 2015 season and he required Tommy John surgery after the 2017 season.

After recovering from his elbow surgery, he reemerged with the Rangers as a full-time reliever. Shorter stints out of the bullpen helped him add a couple of ticks to his fastball, up from 93.9 mph to 95.9 mph. With good ride on the pitch despite a middling spin rate, he’s always been able to use his heater to great effect. But the added velocity gave him greater confidence in the pitch. One of the reasons his control escaped him in his initial stints in the majors was because he tried to nibble on the edges of the strike zone far too much. With the Mets, he located his pitches in the zone just a hair under 40% of the time, well below league average. Last year, his in-zone percentage rose above league average for the first time in his career, and the extra velocity on his pitches gave him even more margin to locate his fastball in the zone with confidence.

That harder fastball paired with a nasty changeup formed the foundation of his repertoire in relief. When he first came up, his changeup averaged around 85 mph but the pitch has gained velocity over the years. Since 2017, his change has sat just under 90 mph and the shape of the pitch has changed with that speed boost, adding a couple of inches of horizontal break. The new shape and speed had significant positive effects on the effectiveness of the pitch.

Rafael Montero, changeup
Year Velocity Horizontal Movement Spin Rate Whiff% xwOBA
2015 84.7 11.6 1796 21.4% 0.412
2016 85.8 14.5 1971 26.3% 0.503
2017 88.0 16.8 2064 29.5% 0.284
2019 89.9 16.3 2062 39.4% 0.244
2020 89.1 15.5 2067 29.0% 0.368
Statcast-era data only, 2014 pitch data omitted

His whiff rate has improved with his revamped changeup, giving him a solid weapon to use against left-handed batters. Over the last two seasons, opposing batters have hit just two extra-base hits off his changeup. As a prospect and a young major leaguer, he flashed a promising slider that has all but disappeared from his repertoire. That pitch could give him a third weapon to use against right-handed batters if he wanted to put the work in to regain a feel for it again.

To get Montero, the Mariners gave up one of the youngest players in their organization. Corniell signed as an international free agent at the start of the 2019 J2 signing period. He was ranked as the team’s 22nd-best prospect by Baseball America this July and the 24th by MLB Pipeline (he slots in at 28th on the Rangers list). He hasn’t yet come stateside, so scouting information since becoming a professional is a bit scarce. Eric Longenhagen didn’t have any notes on him so he asked a scouting contact for theirs. It lines up with what was known about Corniell as an amateur: a big bodied 17-year-old with a 90-92 mph fastball and a couple average offspeed pitches he throws for strikes. His velocity has fluctuated some but still checks the boxes of young projection right-hander. He’s far from a sure thing and still years away from the majors. Perhaps that was why the Mariners were so willing to part with him.

Unless the Player To Be Named Later changes the calculus dramatically, Corniell seems like a fine price to pay for Montero. He wasn’t a core piece of the Mariners rebuild and Montero should help stabilize their big league bullpen immediately. The timing of it all makes it an odd move but the Mariners still have time and money to add to their roster prior to the season. With a few more additions to the bullpen — and elsewhere on the roster — the Mariners could have the rough shape of a contender before their prospect reinforcements arrive mid-season.

Jake Mailhot is a contributor to FanGraphs. A long-suffering Mariners fan, he also writes about them for Lookout Landing. Follow him on Twitter @jakemailhot.

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Monsignor Martinez
3 years ago

They could just sign Trevor Bauer instead and use his “secret recipe”