PEORIA, Ariz. -- This time last year, Paul Sewald was being reassigned to Minor League camp, Drew Steckenrider was laboring, Ken Giles was rehabbing from Tommy John surgery and Diego Castillo was on the Rays.

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Wild how much has changed, yeah?

Sewald and Steckenrider were on Minors contracts, yet they went on to combine for 2.7 WAR (wins above replacement), per FanGraphs, making them one of the stronger relief tandems in the American League. For a bullpen that had an AL-worst 5.92 ERA in 2020, Seattle's ‘21 contingent proved to be a pleasant surprise, and the ‘22 group comes with far more clarity.

“We are more stable this year,” Mariners manager Scott Servais said. “Those guys understand the plan. ... I think just the simplicity of what we've done with those guys has really helped their natural ability come out. Don't try to overcomplicate it. ‘Here's what you're really good at. Let's see if we can be an expert in this area because that's your strength and then see how far we can ride it.’”

For a group that returns mostly intact, here are a few intriguing questions regarding the bullpen entering the season:

Who’s the closer?
There isn’t one ... well, kind of. Servais’ staff is divvying his relievers into leverage “buckets,” then will determine each reliever's most optimal pockets based on recent usage (who’s fresher) and what analytics suggest are the more favorable matchups (who’s got better stuff).

“Then there’s always a little bit of variance, in that that'll lead you one way versus the other,” Servais said.

Sewald was probably 1A and Steckenrider 1B for usage in the highest-leverage moments at the end of last season, with the latter leading the team with 14 saves compared to the former’s 11. But Castillo, who has looked strong in camp and has postseason experience, will also be in the mix. And Andrés Muñoz’s 101-mph fastball certainly stands out as a fit.

“They’ll pitch in different roles, depending on who's available, who's rested and what lineups look like, and wherever their pocket may land,” Servais said. “I don't get caught up in the inning they pitch in. We don't roll that way, and it's worked out pretty well for us.”

Servais has regularly pointed out that some of the game’s most critical outs are much earlier than the ninth inning.

“What it comes right down to for me is ... who gives us the best chance to get the first guy out?” Servais said. “Even if you got a guy for an inning, let's get the first guy out and see what happens from there.”

Who’s got the best stuff?
Every arm in the 'pen does at least one thing really well. Sewald’s slider looks like a frisbee and generated whiffs 43.2% of the time, per Statcast. Castillo’s slider, when it’s on, is perhaps just as good, having held opponents to a .130 batting average. Steckenrider has the big heavy fastball that he rides at the top of the zone and keeps out of the damage zone, which ranked in the 86th percentile last year in barrel rate.

But Muñoz might be the most intriguing. He throws harder than anyone on the staff but is still polishing his slider, which has more sweep than he’d like right now.

“Maybe just tighten it up a little bit,” Servais said, “because you’ve got to land it. You’ve got to throw it for strikes, otherwise they will get on the heater. But it's still not easy to get on that fastball. It’s special.”

The Mariners signed Muñoz to a $7.5 million extension in December despite making just one appearance last year, in Game 162, which shows how high they are on him and his dominant stuff. But given that this will be his first full season back from Tommy John surgery -- as is the case for Ken Giles -- the Mariners don’t plan to pitch those two on back-to-back days.

Are there enough lefties?
Anthony Misiewicz led the team with 66 appearances last year and will continue as the lefty specialist.

“He’s had stretches where he’s been really good, then he’ll have other stretches where it’ll happen really quick," Servais said. "It'd be eight pitches and you look up and there's two or three extra-base hits. ... I'm really hoping he takes a step forward. He could be another guy, pivotal guy, a true pivot guy. If you see a pocket of left-handed hitters or left-right-left and you want to bring him in, you should be able to handle that.”

Beyond Misiewicz, there are multiple in-house options to serve as a lefty swing arm, with Justus Sheffield leading the way. He’s being stretched out more in order to take on that role and to make possible starts, too. Nick Margevicius and Roenis Elias could be options down the road.

But each comes with a few question marks. Misiewicz, like most, was worn down by the end of last year. Sheffield got crushed by righties for a .958 OPS, and Margevicius and Elias are coming off season-ending injuries.

Who’s in? (And, who helps cover the innings?)
With rosters expanding to 28 for the first month, the Mariners plan to carry 15 pitchers into the regular season, and they have two off-days in the first 12 days of the season, so they’re in decent shape.

The loss of Casey Sadler to season-ending shoulder surgery certainly hurts, and though Seattle plugged his spot by adding Sergio Romo, the three-time World Series champion is 39 years old and coming off a down year. Yohan Ramirez has had some of the best swing-and-miss numbers in camp, and Erik Swanson had big moments last year.

The key, in Servais’ mind, is the communication between him, bullpen coach Trent Blank, pitching coach Pete Woodworth and the group.

“I think we do a pretty good job between Trent, Woody and myself, of giving guys a heads-up what it may look like for that given night,” Servais said. “So you're constantly talking about, ‘Hey, be ready to go early tonight.’ In my mind, early might be the fifth or sixth inning. [Or] ‘Hey, I got you later tonight against the bottom of the lineup versus the top of the lineup,’ so they have an idea.”