MESA, Ariz. -- After Hayden Wesneski's most recent spring outing, Cubs pitching coach Tommy Hottovy told the rookie pitcher they needed to go over some scheduling details. Wesneski was then led to manager David Ross' office.

Wesneski was informed he made the Opening Day roster.

"I didn't say a whole lot," Wesneski said. "When David Ross talks, you listen. I didn't talk a whole lot -- I just soaked it in."

On Saturday morning, Ross announced that decision, bringing one aspect of the Cubs' roster into focus. Wesneski will join a rotation that also includes Marcus Stroman, Jameson Taillon, Drew Smyly and Justin Steele.

This will mark the first Opening Day for Wesneski, who assumed the vacancy created by Kyle Hendricks' ongoing return from a shoulder issue. The veteran Hendricks -- the last remaining Cubs player from the 2016 World Series team -- has not missed Opening Day since '14.

"We have so many options," Hendricks said. "That's the really good feeling about this year, is just the depth."

The 25-year-old Wesneski earned the job over the more experienced Adrian Sampson and fellow rookie Javier Assad. Sampson, who was a key part of the rotation down the stretch last year, was optioned to Triple-A Iowa on Saturday. After shining for Team Mexico in the World Baseball Classic, Assad remains in the hunt for a bullpen role.

Asked about Sampson and Assad, Wesneski appeared to get emotional. The pitcher paused for eight seconds, collecting himself and organizing his thoughts, before answering.

"I'm glad to be on their team," Wesneski said. "This is a tough spot to be in. I've learned a lot from Adrian and Assad. ... Those guys are great human beings and they're just as good of pitchers as they are people."

Wesneski added that teams will need more arms beyond the Opening Day rotation throughout the season. He found that out last year, after being acquired from the Yankees for reliever Scott Effross. Chicago's injury-marred rotation had openings down the stretch, and Wesneski found himself in the big leagues.

In six appearances for the Cubs at the end of the season, the righty spun a 2.18 ERA with 33 strikeouts and seven walks in 33 innings. He fanned eight in five scoreless innings in his MLB debut against the Reds and later turned in an immaculate inning on Sept. 22 against the Pirates.

"Last year, we saw just how talented he is and what he can do," Hottovy said. "He's lived up to all the things that we kind of hoped he would be and put on his plate. It's been fun to see him continue to grow.

"He knows there's still a lot he wants to accomplish, and he wants to keep working on. This is kind of that first step for him."

Wesneski said he was in "compete mode" all spring, knowing he could not simply use his outings to work on things like the more established veterans. All the rookie did was fashion a 2.12 ERA with a team-leading 22 strikeouts in 17 innings, while walking six.

In his most recent start on Thursday, Wesneski reached 97 mph on the Sloan Park radar gun. Then on Friday, Stroman noted after his final spring appearance that he sought advice from Wesneski that morning about throwing his slider.

"I haven't been up for long enough for him to come to get advice from me," Wesneski said. "There's a reason why he's pitching Opening Day, right? It's because he's always learning and always figuring out, tinkering with stuff. He learned about it yesterday, and what does he go do? He goes and throws it in the game. It's crazy."

This has all been a whirlwind for Wesneski.

The pitcher said he reminds himself that sixth-round Draft picks like him do not often reach the Major Leagues. Wesneski said he also assumed he would be in Tampa training with the Yankees right now, instead of with the Cubs and winning an Opening Day roster spot. The rookie was grateful to have his parents in Arizona, so he could share the news in person.

All of that added up explains why Wesneski said he was “speechless” in Ross' office.

"He's earned it," Ross said. "He was really excited. Head in the hand. And I think a little bit of, like, relief. But I also know he has a quiet confidence in himself. I think he was just relieved to hear that he earned that and all the hard work pays off."