DETROIT — As pleasant surprises went, Tommy Kahnle was way up there for the first month of the 2017 season, although he’s not alone, not even in the White Sox’s bullpen.

Anthony Swarzak, a nonroster invitee to spring training, didn’t allow a run. But Kahnle, who always has had upper-90s stuff with movement while struggling to command it, has thrown with remarkable efficiency since the Sox called him up April 6 because of an injury to Jake Petricka.

“It’s never been about Tommy’s stuff because Tommy’s stuff is electric,” said first-year Sox bullpen coach Curt Hasler. “He’s throwing the ball downhill better than he ever has, with angle. When you have that kind of stuff in the zone, with angle, it’s tough to deal with.”

Yes, it is. With 19 strikeouts in 19 innings, Kahnle leads AL relief pitchers in total Ks and whiffs per nine. In the Sox’s 6-4 victory over the Tigers on Saturday, he worked a seventh scoreless inning, striking out all three batters he faced in the eighth.

In his last 27 games dating to last season, Kahnle has 37 strikeouts with an ERA of 0.68. He posted a 2.63 ERA in 2016 to lower his career mark to 4.04, but the control issues that have plagued his career surfaced during spring training, and he failed to make the opening-day roster.

Between the White Sox and the Rockies, Kahnle had walked 147 in 268 innings. This year? One walk.

Kahnle has made minor alterations with a smaller leg lift, which helped him get his arm out sooner and his head in line with the plate.

“At the end of spring training we saw some signs,” Hasler said. “Coop (pitching coach Don Cooper) and I talked to him, ‘What is your key?’ It’s throwing downhill. Tommy has embraced that, and he’s been outstanding. As far as anything huge or enlightening (mechanically or delivery-wise), no. It’s about throwing the ball over the plate.

“The guy is blessed with unbelievable stuff.”

Said Derek Holland, who watched Kahnle pitch from the visitors’ clubhouse Saturday after starting the game: “I was in here doing my shoulder stuff and saw one of his pitches and I said, ‘What is that, a slider?’ And it was, no, that was 98. It cut clear across the plate.”

This and that:

• Jose Abreu, who homered twice Saturday, tripled in a run and singled his first 2 at-bats Sunday. Abreu has at least 2 hits in a career-high six straight games. In his last 22 at-bats, Abreu has 12 hits, including 2 home runs, 2 doubles, a triple and 5 RBI.

• Chris Beck’s 2 scoreless innings lowered the Sox’s bullpen ERA to 1.94, best in the majors. “They’re attacking the zone and getting ahead in the count,” bullpen coach Curt Hasler said.

• Right-hander Miguel Gonzalez is 1-2 with a 9.57 ERA at Comerica Park after allowing 6 earned runs (7n overall) in 6 innings Sunday.

• Jacob May, who replaced Avisail Garcia (tight groin), struck out in his 2 at-bats and is 1-for-32.

• This report was produced in partnership with the Chicago Sun-Times. For more coverage, check chicago.suntimes.com.