The Mariners made roster moves involving six players ahead of Tuesday’s 3-0 win over the D-backs that trimmed their Spring Training contingent to 42. With the optioning of right-handers Robert Dugger and Matt Magill to the Minors, and with just three or four days remaining before manager Scott Servais estimates the club will finalize its Opening Day unit, the bullpen picture is coming into clearer scope.

“We’ve got some tough decisions to make here down the stretch,” Servais said. “But the nice thing is we've got a lot of depth. Even some of the guys that maybe don't make our team, they're going to help us at some point.”

Seattle will break camp with eight arms in its bullpen to supplement a six-man rotation. Here’s a breakdown of how Seattle’s relief corps is shaping up:

The virtual locks: Rafael Montero, Kendall Graveman, Anthony Misiewicz
Montero was acquired from the Rangers specifically to contribute high-leverage innings after converting eight saves in as many opportunities last season. He’s exhibited as cool, calm and collected a composure as one could hope for so far in six Spring Training outings, going scoreless in each of his past four appearances. He throws three pitches -- a fastball, changeup and slider -- and can land them all for strikes.

“I think we're going to have to come up with a nickname for him,” Servais said. “I don't know, but he's some kind of suave when he's out there. Nothing speeds him up. I don't know [what’s calmer] -- my resting heart rate at night when I'm sleeping or him in the ninth inning of a game? That will be something we'll have to check out this year.”

Graveman admittedly is still adjusting to life as a reliever after making that transition last September after a benign tumor near his spine forced him to curb his workload. He’s throwing much harder, up to 97 mph on occasion, but he turned to his fastball 60 percent of the time last year. The key for him as a bullpen option will be getting more comfortable with throwing his secondary pitches more regularly.

“That’s been a trying experiment for me and [I've been] talking to as many guys as I could,” Graveman said. “How do you recover? How do you go every day?’ But I get to show up to the baseball field knowing that I have a chance to impact the game every day.”

Misiewicz had a decent 2020, striking out 25 in 20 innings. But he’s also the lone lefty that is vying for big league innings, so his spot is all but secured.

Earning trust: Will Vest, Keynan Middleton, Casey Sadler
Middleton got off to a rough start this spring, serving up five homers in his first four outings that dropped him from being a “lock" for the roster, but he’s come on of late, striking out three of his five batters in his last appearance. Middleton was signed a Major League contract, but he does have a Minor League option remaining.

“Key is starting to get his arm strength,” Servais said. “You saw the velocity starting to creep up, and he's one of those guys that needs it. He leans heavily on his slider, his breaking pitch. But when the fastball is at the 94-95-96 range, it's a heck of a lot easier for him specifically and he goes about it. That's [what] we're starting to see.”

Vest was one of the more intriguing pitchers entering camp, with a changeup that everyone raved about. But he’s been wildly hit or miss -- eight runs in three outings and scoreless in his other five, including on Tuesday. That’s a small sample size, though, and the Mariners might want to roll the dice and keep the Rule 5 Draft selection around a little longer to see what they’ve got.

“The changeup he throws is a different type of change, it's really got some bottom to it,” Servais said. “And he's got a slider as well to help him get back to the count. So, he’s got three viable pitches. He’s very competitive, a really good athlete. And if you're that kind of athlete, you’ve got a chance to get better.”

Sadler has done nothing but throw up zeroes, sans one homer given up last Friday. The right-hander has done just about all he can to earn a spot.

The wild cards: Joey Gerber, Drew Steckenrider
Steckenrider is the epitome of a wild card. He has 113 2/3 innings of big league experience with Miami over parts of three seasons and high-90s velocity that at times has proven to be elite. But there’s a reason he’s in camp on a Minor League contract and fighting for a spot, as command can be a big issue at times. He hasn’t pitched more than one inning per outing since 2018, so it’s unclear if he’ll be a multiple inning candidate.

Gerber, the Mariners’ No. 30 prospect, has been mostly solid this spring and should get strong consideration. One scout observed that Gerber “pitches like his hair is on fire” as a nod to his funky and deceptive delivery.

Swing man: Erik Swanson
The former starter probably has the longest innings leash of any arm vying for consideration, which should play in his favor. But he won’t necessarily be deployed to eat three innings in a pinch.

“I think the longman, per se, is gone in our game,” Servais said. “Again, teams may have multiple guys that can go a couple innings apiece. But just having a guy that sits down there just in case something bad happens. I don't think that's really a spot in a bullpen nowadays.”

Second lefty: Aaron Fletcher
Seattle’s No. 18 prospect got a taste of the Majors with six appearances last season, but it proved to be an eye-opening experience after he gave up six runs on seven hits in 4 1/3 innings. Like many impacted by the odd quirks of last year, the Mariners are hoping those were learning curves more than anything else, and that he doesn’t get too caught up in those numbers and benefits from reflection and trust in his stuff.

Fletcher is unlikely to break camp with the club, but there’s a strong chance he’s a candidate for the alternate training site as an immediate reinforcement.

Rest of the field: Paul Sewald, Domingo Tapia, Brady Lail
Sewald and Lail will be depth pieces for Triple-A Tacoma once it begins the Minor League season on May 6, meaning they’re destined to head to Minors Spring Training in the coming days.

Tapia was in consideration for the big league ‘pen before suffering an oblique injury on March 5. He’s begun his throwing program though and will likely be in the Majors at some point in 2021 once healthy.