HOUSTON -- Lance McCullers Jr. broke into the Major Leagues in 2015, the year Dallas Keuchel won the American League Cy Young Award. Two years later, he was sharing a rotation with Justin Verlander, followed by Gerrit Cole a year later. Then came Zack Greinke, another one of baseball’s best pitchers of his generation.

McCullers watched and listened, soaking up as much information as he could while pitching in the long shadows of experienced veterans, who eventually moved on. Keuchel departed in free agency after the 2018 season, with Cole leaving for the Yankees a year later. Verlander got hurt in the first start of 2020 and hasn’t pitched since, and Greinke battled injuries and inconsistency this year.

In the spring, the Astros gave McCullers a five-year, $85 million contract extension (beginning in 2022) with the goal of making him their ace of the future. Some called it a risky investment for a pitcher who had yet to make more than 22 starts in the season, but McCullers viewed it as a chance to put down roots in his adopted hometown. That’s why he’s so pumped up to take the ball for the Astros in Game 1 of the American League Division Series on Thursday against the White Sox at Minute Maid Park.

“This organization, this city, it means a lot to me and my family,” he said. “They've always treated me with a lot of love and respect, so I always try to give that back.”

This won’t be the biggest start of McCullers’ career. Far from it. He started Game 7 of the 2017 World Series and Game 7 of the 2020 AL Championship Series, in addition to five other playoff starts. But getting the ball to open the playoffs, being the pitcher who has a chance to set the tone for October, brings a certain responsibility.

“I'm not putting too much stock in it,” he said. “I feel like I have had a nice season, the team and organization, Dusty [Baker], they recognize that to give me the ball Game 1, which I'm very excited about. At the same time, I'm going to go out there and just be myself. I feel like what I bring to the table, I have the ability to pitch with anyone. I'm excited to just get out there and give my best effort for the guys.”

McCullers, 28, had his best season as a Major Leaguer, going 13-5 with a 3.16 ERA, which was the second best in the AL. He led the AL in opponents’ batting average and OPS and had the fewest hits per nine innings. He was the easy choice to start Game 1 for the Astros, with Greinke likely shuffling into a bullpen role in October.

“He’s our ace,” said close friend and teammate Carlos Correa. “This is what aces do. They take the ball in Game 1. I’m looking forward to playing behind him. He’s built for these moments and he embraces them, and he goes out there and he’s a monster in the playoffs.”

Thursday will be McCullers’ eighth career playoff start, which will tie Greinke for third most in Astros’ history. Keuchel started nine playoff games from 2015-18 and Verlander started 14 postseason games for the Astros from 2017-19. McCullers has also thrown in relief seven times in the postseason, most notably when he tossed four scoreless innings to close out Game 7 of the 2017 ALCS. He threw five times in relief in 2018 after tearing his ulnar collateral ligament.

Even though he was injured midseason in 2018, McCullers postponed his Tommy John surgery. The Astros were defending their World Series title and he wanted the ball, even if it meant throwing an inning here and there. It’s that doggedness that makes him cut out for October.

“It's just a privilege to be able to play October baseball,” McCullers said. “My father played many years in this game, seven, eight years. I know guys who go their whole careers and never get to a postseason in general. So being able to be here, I don't know, my fifth, maybe sixth time, it's a blessing. Being able to look around the locker room and see those faces that kind of broke through and did it for the first time in 10 years, bringing postseason baseball back to Houston, it's really cool and special to see those guys here because, at the end of the day, I really do feel like Houston is a baseball city. I feel like they love baseball, and we get to give them that joy.”

McCullers’ evolution from short-haired rookie to long-haired ace is the product of time, as well as adaptation. He relied on a 95 mph fastball and sharp curveball in 2015 but now incorporates a slider that he throws more than his trademark curveball. He’s become a ground-ball pitcher, too, leading the AL at 56.9 percent grounders this year.

At the end the day, he’s the same competitor he’s been since 2015.

“I have to go out there and just continue being who I've been this season,” he said. “I feel like I've added a lot of different layers to my game as far as pitching goes. Physically and mentally, I feel like I'm probably in the best spot I've been. So I just want to go out there and put my best foot forward.”