When the offseason started for the White Sox, there wasn’t much of a late-inning bullpen group to speak of.

Gregory Santos is expected back by Opening Day after finishing the 2023 season on the injured list. But who knows if he’ll reassume the closer’s role he was handed after Liam Hendriks’ comeback season ended with Tommy John surgery. As good as Santos was out of the bullpen, he struggled after being officially crowned the team’s closer, with an 8.68 ERA and three blown saves across his final 10 appearances, woeful compared to the 2.53 ERA he had in his first 50 outings of the campaign.

But past Santos, there weren’t many late-inning arms among the White Sox’ relief corps, especially after first-year general manager Chris Getz shipped veteran lefty Aaron Bummer to the Braves in an early-offseason trade. Garrett Crochet, another southpaw, will be getting a conversion from a reliever to a starter this spring.

Since dealing Bummer, though, Getz has added a couple veterans on free-agent contracts that bolster that group in the back, with John Brebbia the latest and perhaps most impactful.

The White Sox made their one-year free-agent pact with Brebbia official Monday, a deal worth $5.5 million, making Brebbia the second highest paid addition of the offseason after starting pitcher Erick Fedde, who will make $7.5 million in 2024. Brebbia’s arrival shows the continued influence of new pitching czar Brian Bannister, who counted Brebbia among his pupils during his years with the Giants.

After missing 2020 with Tommy John and spending much of 2021 in recovery mode, Brebbia led the National League with 76 appearances in 2022, when he posted a 3.18 ERA, his best mark since the 2.44 ERA he had as a rookie with the Cardinals in 2017. Last season, he barely kept his ERA below 4.00 and missed three months with a lat injury.

That 2023 puts him in Bannister’s self-declared “sweet spot,” someone who got away from past success and can be reshaped into an effective arm. Most of the White Sox’ pitching acquisitions this winter fit the same mold.

More interestingly, perhaps, is Brebbia’s experience as an opener, a job he did often with the Giants. The White Sox have utilized openers sparingly since the practice became en vogue thanks to Kevin Cash and the Rays. Rick Renteria voiced an initial distaste for the idea, and Tony La Russa expressed his desire to stick to the classic five-man rotation. That doesn’t mean either man completely stayed away from openers, but White Sox fans have typically only seen them used when a starting pitcher has been unable to go due to injury. It’s been a strategy used only to get the White Sox through tricky spots in the schedule.

The Giants, under Bannister’s watch and with Gabe Kapler as manager, had no such compunctions and used them frequently in recent seasons. Bannister is obviously now running the pitching side of things for the White Sox, and Getz has repeatedly used the term “starting-pitching innings” when talking this offseason. Now Brebbia, who made 21 “starts” for the Giants in 2022 and 2023 is aboard.

Could the White Sox be shifting to using openers on a far more regular basis?

We’ll have to wait and see exactly how it plays out. The team has a large volume of starting-pitching candidates, even if few can be counted as exciting options among fans. Fedde seems the most reliable of the newcomers after winning the Korean baseball MVP last year, but there are large questions about his ability to translate his overseas success to the majors, where he had little success in six years with the Nationals.

And the questions only get bigger from there when it comes to the likes of Michael Kopech, Chris Flexen, Michael Soroka, Touki Toussaint, Jesse Scholtens, Jared Shuster and a host of minor league signings who keep steadily rolling in.

Given all that uncertainty — including whether staff ace Dylan Cease, whose name has been in trade rumors all winter, will even be on the team come Opening Day — perhaps cobbling together games with openers is a more appealing way to go. Certainly Brebbia has shown he can do it, and the White Sox might believe they have others who can, as well.

But Brebbia, too, could arrive as the team’s most trusted late-inning arm, with Santos’ late-season numbers not exactly making a repeat of his 2023 a slam dunk. Getz also added veteran Tim Hill to the mix as a free agent, and he figures to be one of those late-inning arms, though he’ll need some of that Bannister magic after posting a career-worst 5.48 ERA last season for the Padres.

Past those two additions, holdovers Tanner Banks, Matt Foster, Deivi García, Jimmy Lambert, Sammy Peralta and Lane Ramsey, plus any of those aforementioned starting candidates who don’t make the rotation, figure to battle it out for bullpen spots. The White Sox also added Alex Speas as a waiver claim in October and Shane Drohan as a Rule 5 pick in December. Pitching prospect Jordan Leasure, acquired in a deadline trade with the Dodgers, put up big strikeout numbers in the minor leagues and gave up just one run in eight outings in the Arizona Fall League.

It’s all a long way of saying that the team’s late-inning group is far from finalized, even if it has been bolstered by the arrival of Brebbia. Pedro Grifol voiced at the end of last season that things have a way of working out:

“I think the cool thing about a bullpen is that it can come from anywhere,” Grifol said in September. “You might have a starter in the minor leagues that all of a sudden has a really good spring training and you feel he’s got the stuff, but you don’t want to push him to start in the big leagues yet, you might want to preserve innings or you don’t want to give him that task of 30 starts. You start him off in the bullpen, and all of a sudden you’ve got a big-time dude out there. Or it can come from a non-roster invite, like (Keynan) Middleton. Or it can come from a trade, like Santos, where you identify a big arm. … Who knows?

“The good thing about a bullpen is they just show up. It just happens. I remember Liam starting for us in Kansas City. And then the next thing you know, he’s in the bullpen in Oakland and he’s having a great season in middle leverage to a little bit later leverage. And the next thing you know, he’s one of the premier closers in the game.

“That’s the cool thing about building a bullpen, you have so many different avenues that you can use and resources you can use to fill it out. It’s kind of neat.”

But even if there is some truth to that, certainty is in short supply. Not that certainty always works out. Former general manager Rick Hahn always pointed to the year-to-year volatility of relievers making it difficult to project how roles in a ‘pen would be cemented, and that was well proven by a seemingly loaded group falling apart by the middle of last season. Of the team’s Opening Day relief corps, only Santos and Lambert (who was shuttled back and forth between the majors and minors) remain with the organization, and most were gone by the trade deadline.

Let’s just say it’ll be a busy spring for the White Sox as they try to figure out how the pieces of their pitching staff fit together.