CINCINNATI -- Even at his best, when he is baffling hitters with one of baseball's elite sweeping sliders, Hayden Wesneski is his own toughest critic. The Cubs rookie's lofty personal expectations and constant search for ways to improve played a role in securing a spot in the Opening Day rotation.

Prior to Tuesday's 12-5 win over the Reds, Cubs assistant pitching coach Daniel Moskos laughed when asked if Wesneski has always been that way. Moskos has known the pitcher since the coach's days working in the farm system of the Yankees, who traded Wesneski to Chicago last summer.

Whether it's a game or a bullpen session, Wesneski holds himself to a high standard.

"Oh yeah, always," Moskos said. "I can't tell you how many bullpens I've been together with him, and I have yet to hear him come away saying, 'That was a really good 'pen today.' Even though we'll be standing back there and be like, 'Wow.'"

Wesneski, Chicago's No. 5 prospect, will have plenty to pore over in the self-assessment of his season debut, in which he was pulled after 4 2/3 innings. The right-hander struck out four and allowed three runs -- two came via solo homers -- on six hits and two walks.

There were positives for Wesneski in an outing in which he was admittedly "amped" to get his season rolling. He touched 98 mph with his fastball and generated nine whiffs. And given the amount of traffic he dealt with on the basepaths, Wesneski limited the potential damage.

A flurry of late offense -- the North Siders churned out 11 runs in the final four innings -- helped him escape with a no-decision.

"I'm not happy with it," Wesneski said. "But I'm not upset with what happened. I threw a bunch of strikes. I gave our team a chance. It didn't go as planned, but I mean they're swinging it well. I'm glad I threw a bunch of strikes and I'm glad we got the win."

The Cubs acquired the 25-year-old Wesneski at the Trade Deadline last year for reliever Scott Effross. Down the stretch with the Cubs, the righty fashioned a 2.18 ERA with 33 strikeouts in 33 innings. This spring, Wesneski backed that up with a 2.12 ERA and 22 strikeouts in 17 frames.

That combination of performance, coupled with the way Wesneski handles himself behind the scenes, convinced the Cubs to name him the No. 5 starter with veteran Kyle Hendricks (right shoulder) on the injured list. Wesneski is young in age and experience, but he has a veteran presence about him, both in how he thinks about pitching and the confidence he displays.

"He's been really impressive," Cubs president of baseball operations Jed Hoyer said. "He seems unbelievably comfortable -- in a good way. He's talking to all the veteran pitchers. Everything about the way he carries himself is that he belongs in the rotation and he belongs to the big leagues."

Moskos said the next step for Wesneski to keep unlocking his potential is to continue to improve with his pitch sequencing. The rookie has already made great strides in that process, which began in earnest during his time at Double-A Somerset in 2021.

That summer, Wesneski arrived in Somerset -- where Moskos was the pitching coach -- after posting a 1.49 ERA in seven outings at the High-A level. Then, Wesneski struggled to the tune of a 7.01 ERA in his first seven appearances at Double-A.

"It was a very big learning curve for him," Moskos said. "He started to realize, like, 'OK, I've got to pick better times to use things.' He got roughed up a little bit, and then he really started dedicating himself on that preparation side."

Moskos recalls how Wesneski started to sit next to him in the dugout, charting pitches and asking the pitching coach about certain in-game sequence decisions by other arms. The information gathered in those conversations helped Wesneski turn a corner. He went 7-0 with a 1.86 ERA in his final eight turns at Double-A before a promotion to Triple-A Scranton/Wilkes-Barre.

"That's when you started really to see the dots being connected," Moskos said, "and [seeing] him start to really take off on that front."

Wesneski continued to carry that into '22, when he reached the big leagues and opened eyes over the final month of the season. The Cubs are counting on the young pitcher to keep making strides this season.

This outing was just the first step in this next phase of Wesneski's development.

"He'll be better," Cubs manager David Ross said. "Probably not his best -- he'll probably tell you that. But it's a nice 'W.'"