KANSAS CITY, Mo. — A spot start? A save opportunity?

A third of an inning? How about five?

It’s all the same for White Sox relievers Tyler Alexander and Mike Vasil, who have taken on Swiss-army knife roles for a surprisingly stout bullpen that has emerged as one of the best in baseball since the All-Star break.

The journeyman lefty Alexander and the rookie righty Vasil are serving important bulk relief roles to help back up a young rotation grinding to the end of the season.

But they’ve also each logged their first career saves and taken the ball in other high-leverage situations for the improved second-half squad — and they’re never quite sure what’s next.

“I like the chaos of what I’m doing now,” Alexander said before the Sox’ series opener Friday night in Kansas City. “It’s fun, it keeps it entertaining. And I think I’m good at it, too.”

Chaos sounds about right for a guy who took a 90-minute Uber to Chicago from Milwaukee when the Sox picked him up in early June off the heap from the Brewers, who had designated Alexander for assignment. He arrived midgame and pitched three strong innings.

A 4-10 record with a 4.27 ERA entering play Friday might not scream “go-to guy,” but Alexander has been one of manager Will Venable’s most reliable arms this season over 38 games and 78 innings. He’s turned it up late in the summer, limiting batters to a .177 average since the break.

“I’ve always thrown harder in the second half,” said Alexander, who was born in Chicago but mostly grew up in the Dallas area. He’s still got family in Oak Park.

An 80-mph sweeper has helped keep batters off-balance against Alexander’s 90-mph fastball. “You just prepare your body everyday to throw.”

Jayne Kamin-Oncea/AP Photos

The 6-foot-5 Boston native Vasil (5-3, 2.53) brings a little more velocity with 94-mph four-seamers and sinkers, giving the Sox more than they could’ve expected for the Rule 5 Draft pick whom they claimed off waivers late in spring training.

Vasil has also shown a fire on the mound that has raised the energy in the clubhouse, and he keeps a Batman mask in his locker, in case there was any doubt of his superhero aspirations.

“I would like to think most of the times I take the mound, it’s a Batman situation,” Vasil said. “It’s not like we’re just drawing any innings. We’re going out in tough situations, high leverage, whatever it is, and giving length. Any time that happens, it’s awesome.”

While Alexander and Vasil are relishing ever-evolving roles, Venable is grateful to know what he’s getting when he calls for either one of the versatile relievers.

“I’m not sure that you could look at two guys and their roles that have helped us more than they have,” Venable said. “To be flexible enough coming out of the bullpen in short stints, then in longer stints, and to do it with the type of quality that they’ve been doing, it’s made all the difference for us to be able to navigate different parts of the year.”

That’s especially important in the final two months of the season with starters Shane Smith, Davis Martin and Sean Burke approaching or eclipsing career highs in innings pitched.

The whole bullpen helped carry the Sox to a .500 record in 24 games since the break, with an overall 2.84 ERA that marked the third-best in MLB. They were holding opponents to a .204 average from July 18 through Thursday, with 111 strikeouts that were good for second-most in the majors.

“We’re just kind of in a nice groove,” Alexander said. “One guy building off the other — one guy throws well, the next guy wants to throw well. We’re just pitching how we always pitch and it’s going our way.”