ST. PETERSBURG, Fla. — White Sox bullpen coach Curt Hasler is confident right-hander Tommy Kahnle can keep this going.

The hard-throwing 27-year-old has shown flashes of excellence during his four-year career but hasn’t really sustained it. But it’s June, and Kahnle still is humming along as perhaps the toughest pitcher to face out of the Sox’ bullpen.

“If they trade [David] Robertson, I would make Kahnle their closer,” a National League scout said.

Scouts are watching Kahnle closely in case the Sox are willing to deal him for a prospect or two by the trade deadline. At his age, and because of the up-and-down, year-to-year volatility relievers are often subject to, it might make good sense to move Kahnle while his value is high.

And right now he’s a handful for opposing hitters.

“When he’s throwing the ball downhill and commanding two, if not three pitches, for strikes, he can sustain this indefinitely because his stuff is so good,’’ Hasler said. “And now it’s in the zone where he wants it.’’

Kahnle ranks sixth among American League relievers with a 1.59 ERA, and is fourth in strikeouts per nine innings (15.59) and fifth in WHIP (0.80). The Rays’ run against him in the Sox’ 4-2 win Tuesday snapped an eight-game scoreless appearance streak.

Kahnle’s fastball is averaging 98 mph according to Brooks Baseball and his changeup, at 91 mph, “is devastating,’’ Hasler said.

“He throws it hard, but he throws his fastball hard, too. He throws it with good arm speed and it comes out like a fastball and it has late action. When you have 95-100, they have to gear up for that, and when you have 95-100 in the zone, you have to respect that. Then here comes the changeup. It’s a pretty devastating mix.’’

Kahnle didn’t make the team out of spring training because of command issues, but injuries in the bullpen opened a door, and he has taken advantage.

“Focusing on the glove a little more to keep my head in line, and keeping my body from falling off all the time and being inconsistent,’’ Kahnle said Wednesday. “It’s really helped. Trying not to lose that focus.

“Really it’s mental. You have to be mentally tough out there. You have to keep telling yourself, ‘I’m not going to let myself stray away from that.’ Really dig down I guess.’’

Kahnle not only stuck with the big club, he earned a promotion as well to high leverage seventh- and eighth-inning work.

“I like the opportunity, and I’m really looking to seize it and hold on to this,’’ Kahnle said. “I’ve always had that mentality to pitch late in games. I’ve always kind of strived toward it, I guess. It just feels good. I like the emotions it brings and the competitiveness at the end of games.’’

A fifth-round draft pick by the Yankees in 2010, Kahnle was plucked by the Rockies in the Rule 5
draft before the 2014 season, but the Rockies traded him to the Sox in a minor deal for right-hander Yency Almonte in 2015. Kahnle had a 2.63 ERA in 29 games. He also posted a 3.00 ERA in 23 games at Class AAA Charlotte.

It’s all coming together for him now, the only bump along the way this year being LaTroy Hawkins’ blind-side on-air comment that Kahnle was a bad teammate.

Loud teammate, yes, his teammates say, but not a bad one.

“He’s a good kid, man,’’ Hasler said. “He’s a great kid. As he’s going well you don’t do too much really, you just keep him going with what he’s doing.’’

Follow me on Twitter @CST_soxvan.

Email: dvanschouwen@suntimes.com

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