Breaking down Mariners' new roles in 'pen

NEW YORK -- It’s been one week since the Trade Deadline, and the dust has settled on the Mariners’ roster restructuring. No unit had more turnover than the club’s biggest catalyst this season: the bullpen.

As Seattle stares down the final eight weeks of the regular season, here’s a breakdown of where things stand with its relief corps.

Who’s the closer?
Diego Castillo has all the makings for that role. He has 15 saves this season and has been the Mariners’ final pitcher in three of the four games he’s appeared in since coming over via a trade with the Rays. But Paul Sewald is still getting the highest-leverage opportunities, regardless of inning.

Like most clubs, the Mariners are looking at matchups above all, and Sewald has been installed against the opponent’s best hitters. Such was the case Thursday, when he was called on in the seventh inning to face the top of the Yankees’ lineup with a one-run lead but ended up allowing a go-ahead homer to Joey Gallo.

That long ball was more a product of the short-porch environment at Yankee Stadium than a mistake by Sewald. Seattle will send him out there in the same situations again on days he’s available. But between Sewald and Castillo, the Mariners believe they are well positioned for a game’s most critical outs.

What’s the skinny on Castillo?
The fourth-year righty has a power sinker and slider combo, throws his heater at 95 mph and powers down the mound at 250 pounds. He passes the eye test in tangible form, but just about every analytic metric likes him, too. Castillo ranks in the top 10 percent of MLB in quality of contact, expected ERA and strikeouts.

But Castillo also brings a postseason pedigree, having pitched in 14 playoff games while holding hitters scoreless in all but two of them.

“What's not to like?” Mariners pitching coach Pete Woodworth said. “Power sink, a really good freakin’ slider and a ton of experience in high-leverage situations, in postseason games and meaningful games. The guy has been doing this for the past three, four years in the biggest stage and the biggest points of the game, which, looking at our bullpen, we don't have a ton of that. So that's one of the biggest positives from Diego, is just a ton of experience in the eighth, ninth innings in meaningful games.”

Who’s the new Chargois?
There’s an open opportunity here for Casey Sadler to step into the role that JT Chargois held before he was dealt to the Rays in the Castillo trade -- the first man up after the starter, which at times can be in a pinch and with traffic on the bases. Joe Smith could also carve out a spot here. Same for left-hander Anthony Misiewicz, though the Mariners would preferably like to allocate his innings against lefties.

“You're mixing and matching, trying to put guys in spots where it gives us the best chance to get the outs that we need to get, the best spot for that player to go out and produce,” Mariners manager Scott Servais said. “Again, I think we have enough. I really do. Joe Smith has been a nice addition. Misz has thrown the ball really well. You talk about what Sadler has done since he’s come back, [Drew] Steckenrider, and we’re not even talking about Sewald and Castillo.”

Who’s the name to watch?
Smith. His numbers jumped off the page for the wrong reasons when he came over in the trade that sent Kendall Graveman to Houston. Smith had a 7.48 ERA and an opposing slash line of .376/.416/.581 in 27 games for the Astros this season.

Even Mariners general manager Jerry Dipoto said after the trade that it probably looked odd as a standalone deal, but he also pointed to Smith’s expected metrics being much better than his actual results -- a 4.10 xERA compared to a 6.57 ERA this year entering Friday, for example.

In the small sample since his arrival, Smith has thrown three hitless innings, albeit in low-leverage situations.

“You have a guy who has a lot of underlying detail suggesting that his year should be better than it actually has been,” Dipoto said. “And Joe Smith is an easy guy to trust and to root for. So hopefully, he can contribute down there as well.”

Can Seattle withstand the loss of Graveman?
There’s no dodging the fact that Graveman’s departure left Seattle’s clubhouse emotional. And he will be deployed against the Mariners in their nine remaining games against the Astros, which could become especially tough with those games directly impacting the postseason chase.

Mariners management justified the moves by looking to 2022 and beyond, with Castillo under club control through ‘24 and Graveman set to become a free agent this offseason. The bullpen with Graveman put the club on the edge of a postseason spot, and the reinforcements will be just as vital to keeping it in the hunt.