PITTSBURGH -- Paul Skenes' stuff was as electric as advertised.

A fastball that reached at least 100 mph 17 times. A slider that left major leaguers shaking their heads. An invention called a "splinker" that is a hybrid of a splitter and a sinker and dips and dives unlike any pitch anywhere in baseball.

Yet even at age 21, the Pittsburgh Pirates rookie knows all the "oohs" and "ahs" and knee buckles a ball that at times seems to explode out of his right hand can produce won't matter if he can't control it.

So while there were some positive takeaways from his major league debut Saturday -- seven strikeouts over four-plus innings and much, much later a 10-9 victory over the Chicago Cubs -- the top overall pick in last year's draft understands there is more work to be done.

He needed 84 pitches to get 12 outs, issued a couple of walks, hit a batter and was charged with three runs. For a player whose workload will be closely monitored, that's not nearly as efficient as he'd like.

Yes, there were moments of brilliance in front of a crowd of 34,924 that included his famous girlfriend, LSU gymnast and social media influencer Livvy Dunne.

There were also moments when the Cubs offered a reminder that for all his talent, Skenes is still a rookie who has been a full-time pitcher for less than two years. And it will take more than testing the limits of the radar gun to succeed at baseball's highest level.

Pirates manager Derek Shelton blamed Skenes' inconsistency on the kind of nervous energy every player feels when he reaches the majors. Skenes, who posted a 0.99 ERA in seven starts for Triple-A Indianapolis before being called up this week, declined to get into specifics.

"You can chalk it up to a number of things," Skenes said. "But it just wasn't as sharp as it's been."

Still, he said the day was everything he had hoped it would be.

"Once-in-a-lifetime experience, for sure," Skenes said in his on-field postgame interview on Sportsnet Pittsburgh. "Just an awesome experience from the first pitch, and I'm glad we got a win."

Skenes' average fastball velocity was 100.1 mph, the highest of any Pirates starter in the pitch-tracking era (since 2008). His 17 pitches of at least 100 mph were tied for the third most by any player in his season debut since 2008. And he became the first Pirates pitcher aged 21 or younger to record at least seven strikeouts in his major league debut since Nick Maddox fanned 11 against the St. Louis Cardinals in 1907 -- 95 years before Skenes was born.

Maddox played just four seasons. Expectations are decidedly higher for Skenes.

The Pirates teased his call-up Wednesday and his highly anticipated arrival gave PNC Park a playoff-like atmosphere, or at least as much as it can feel like October in mid-May for a team that hasn't reached the postseason since 2015.

Fans lined up two and three deep behind the Pirates' bullpen beyond the center-field fence to try and catch some of Skenes' pregame routine. Nearby, the team store under the left-field bleachers did a brisk business, with some ponying up $200 for jerseys with Skenes' No. 30 stitched on the back.

It's been a dizzying rise for Skenes from somewhat anonymous Air Force Academy cadet to College World Series MVP at LSU to a record $9.2 million signing bonus to possible franchise cornerstone. And yet he looked plenty comfortable.

Skenes, black socks pulled up high against his white pants, confidently strolled out of the dugout and bounded over the third-base line to start what he has likened to the end of one portion of his life and the beginning of another.

A significant portion of the crowd stood while Skenes warmed up as "Cue Country Roads" by Charles Wesley Godwin blared over the speakers.

Then Chicago designated hitter Mike Tauchman stepped into the batter's box, and hype gave way to reality. Skenes unfurled his 6-foot-6 frame and with his funky delivery fired a 101 mph fastball to Trautman that plate umpire Paul Clemons called a ball.

Six pitches later, Trautman was walking back to the dugout after swinging at another fastball -- 100.9 mph this time -- that he tipped into catcher Yasmani Grandal's mitt for Skenes' first strikeout.

His second followed three pitches later.

Cubs right fielder Seiya Suzuki took a pair of called strikes -- the second an 87 mph slider that left Suzuki shaking his head -- before flailing at another slider.

Chicago center fielder Cody Bellinger worked a walk, but only after taking a ball that registered 101.9 mph, the fastest by a Pirates pitcher since Major League Baseball began tracking pitch speed in 2008.

Skenes worked out of the inning by getting Christopher Morel to fly out to deep center. A walk, a hit batter and a single in the second loaded the bases with one out. No matter. Yan Gomes struck out looking at a fastball and Tauchman grounded out to second.

The next two innings were more of the same, with Skenes -- who retreated to the tunnel behind the dugout when the Pirates were hitting -- mixing triple-digit fastballs with offspeed stuff that remains a work in progress. Hoerner went deep on a hanging first-pitch slider.

Tauchman led off the fifth with a double and Suzuki followed with an infield single. Shelton then made his way to the mound to take Skenes out, while many fans rose to their feet.

Skenes spent the next several hours -- including a 2-hour, 20-minute rain delay -- trying to decompress. He hung out in the dugout with a few of his teammates, some of whose big league careers began when he was in grade school.

On Sunday, he'll wake up and try to slip into the rhythm of the season and begin preparing for his next start, likely a rematch with the Cubs at Wrigley Field late next week. There will be considerably less buzz. And hopefully fewer jitters.

"It's gonna be nice to get into a routine for sure," he said. "I'm big on routines, so the last week has been tough. But the bottom line is you have to go out there and pitch."

The Associated Press contributed to this report.