White Sox’ Michael Kopech much improved in second start

GLENDALE, Ariz. — Right-hander Michael Kopech has a big arm, and he’s proud of it. Those 100 mph readings on the radar gun are crowd-pleasers, and Kopech enjoys playing to the fans.

It took the highly regarded prospect one spring-training outing to know it’s throw for show and pitch for dough.

“These are major-league hitters,’’ he said, reflecting on a four-run stain in his first inning in a Cactus League game almost two weeks ago.

Command of the fastball, as well his secondary pitches, will eventually determine how good he’ll be. Kopech, 20, wants to make the changeup his best secondary pitch, and that’s going to take some time. It rates behind his slider right now, he said.

“But I really would like to make my changeup my go-to No. 2 and use the slider when necessary,’’ he said. “The changeup is a devastating pitch when you have control over it and are comfortable with it. That’s what I’m trying to establish.’’

The White Sox’ radar gun had Kopech touching 101 mph and averaging 98 in his three innings of one-run ball Sunday against the Rangers. But after working on the back fields with coaches Don Cooper and Curt Hasler after his last start against the Mariners, Kopech had better command of his slider and changeup, and the results were predictable.

It didn’t start out so well. He gave up a run on three pitches out of the gate (single by Delino DeShields, stolen base, double by Nomar Mazara) but held steady and unleashed that big talent the Sox are banking on — striking out Joey Gallo, Will Middlebrooks and James Loney in order.

Kopech got Gallo and Loney swinging on elevated fastballs and Middlebrooks with a slider. He tacked on two more scoreless innings and finished with four strikeouts — getting Middlebrooks taking a fastball on the outside corner — and one walk.

“I only threw four or five [changeups], but the four or five that I threw were effective, where I wanted them,’’ Kopech said. “Even the ones that were balls, I still put them where I wanted.’’

Kopech seems ticketed to start the season at Class AA Birmingham, but you can tell from talking to him that he believes he can pitch in the majors now. And striking out the 3-4-5 hitters in a major-league lineup would seem to indicate he can.

“Obviously, I have a lot of respect for those guys; they are great hitters,’’ he said. “But when I’m on the mound and they’re in the box, he’s just another hitter.’’

But there’s no need to rush. Twenty is so young.

“The ultimate goal is to dominate at the big-league level,’’ Kopech said. “I realize that [the major leagues] might not be right away, but it’s about trusting the process we have going on.’’

Manager Rick Renteria would only say that another start is a possibility for Kopech.

“We still have a schedule for him to follow should he not,’’ Renteria said.

There’s no question about the ability of Kopech, who came from the Red Sox with Yoan Moncada and two other prospects in the Chris Sale trade. While most scouting experts peg Kopech as the Sox’ third-best prospect, ESPN’s Keith Law rates him No. 1.

That’s based on talent. But it will take more time to develop consistency with his fastball command and secondary pitches. Meanwhile, this outing gives Kopech something nice to put in his pocket.

“A little better command and down in the zone,’’ Renteria said. “He was actually throwing some breaking balls over for strikes.

“I thought he showed good poise in his first start, but his command was better.’’

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Email: dvanschouwen@suntimes.com