The first time Chicago Cubs outfielder Pete Crow-Armstrong was on the same field as Pittsburgh Pirates rookie pitcher Paul Skenes, their roles were reversed.

The two were playing together on the United States 12U national team, in Mazatlan, Mexico, in 2014, well before Skenes would become baseball’s biggest pitching phenom. Crow-Armstrong pitched in the tournament, but Skenes never took the mound.

“He was a scrawny catcher,” Crow-Armstrong recalled with a smirk. “I took home the lowest ERA in the tournament, but he’s the No.1 pick.

“I guess things changed.”

Over the first 10 innings of Skenes’ major league career, Crow-Armstrong and the Cubs got a firsthand view at just how much.

The No.1 overall pick from last summer’s loaded MLB draft has wowed the baseball world with his mound presence and electric stuff, throwing 29 pitches at 100 mph or faster — already the most by any starter this season. Just two starts into his big league career, Skenes’ outings have become must-watch events.

“Watching him is like looking at your odometer on the autobahn,” one rival scout said. “It’s 100 all day long.”

In his first major league start on May 11, Skenes said he didn’t really feel like himself. Perhaps it was due to all the hype leading up to the day or just the nerves that come with a major league debut, but the tall right-hander gave up three runs on six hits and two walks in four innings at home against the Cubs. Six days later, in his first road start, Skenes showed what all the hype was about.

“It’s not an easy game to play but it’s a lot easier when you have fastball command and command over your pitches,” Skenes told ESPN after his second game. “It wasn’t necessarily working in my debut, but it was working this time.”

Skenes struck out the first seven batters he faced. He finished the day with 11 strikeouts over six hitless innings, setting a franchise mark for the most K’s by a Pirates pitcher at Wrigley Field, one of the game’s most iconic venues.

“It’s frickin’ Wrigley Field,” Skenes said. “It was sweet.”

Any thought that the Cubs would have an advantage seeing the same pitcher within a week were erased with every eye-popping pitch. Skenes averaged an incredible 99.3 mph on his fastball, 94.8 on his splitter, 86.8 on his change, 84 on his slider and 80 on his curve.

Mike Tauchman was among the many Cubs hitters who couldn’t catch up to Skenes’ stuff. Chicago’s DH struck out three times, including a swing-and-miss on a 100-mph fastball that marked the end of Skenes’ day in the bottom of the sixth inning.

“The fastball command was good,” Tauchman said. “And then he was able to tunnel that splitter/sinker — or whatever he calls it — off of it. And throw those all competitively. When you’re dealing with someone with that velocity and command, and they make you make split-second decisions — he did a good job.”

That combination pitch is called a splinker (though officially tracked as a splitter by MLB Statcast), and the new wrinkle in Skenes’ repertoire is threatening to make the already-daunting task of facing the sport’s best young pitcher downright unfair.

“It tunnels well off his fastball. It has enough of a similar look off his hand,” Tauchman said. “It has more run and drop than his fastball does.”

Skenes mostly stuck to his fastball/splinker combo, mixing in enough of his other pitches to keep the Cubs guessing and showing what separates him in an era full of hard-throwing, young pitchers.

“That’s what attracted us to him,” Pirates manager Derek Shelton said. “His ability with the pitch mix. You can look up and see 101 mph and get excited about it. The fact that he can spin the ball behind in the count, you don’t see guys come out of college a year ago that have the ability to do that.”

After managing two weakly hit groundouts against his former teammate, Crow-Armstrong offered his takeaways for the next teams to face Skenes.

“Being able to limit the top for him or limit the bottom is going to be very important because his stuff plays really well at both levels,” Crow-Armstrong said. “Anything that runs 18 inches at 100 mph is pretty tough.”

Skenes said his phone blew up after the dominant performance, but admitted “that’s been the norm for a while now” since he entered the spotlight while leading LSU to the College World Series title. One of the first people Skenes heard from after the outing at Wrigley was Ryan Theriot, a former LSU and Cubs infielder. The pitcher’s performance reminded Theriot of a former Chicago strikeout artist.

“I know the [Stephen] Strasburg comps, but I feel like it’s more like Kerry Wood in his prime,” Theriot said in a phone interview. “Just the demeanor. I’m not talking about the stuff. I’m talking about the attitude and the demeanor.”

That attitude is why the Pirates are confident he can handle the pressure of being a budding face of the franchise at such a young age. It helps that before transferring at LSU, Skenes attended the Air Force Academy and spent two years as an aspiring cadet.

“You definitely have to be able to handle stuff if you go to the Air Force,” Skenes said. “That taught me how to not care too much about struggling and about staying steady.”

From a somewhat rocky first start to a dazzling follow-up performance that has the whole baseball world watching, that mindset is already paying off for MLB’s newest ace.