"In my opinion, we got the best prep pitcher in the country, and we got the best prep player in the country, and they're both young and they both have unlimited ceilings," Luhnow said.
McCullers, accompanied by his father, former Major League pitcher Lance McCullers Sr., his mother, brother and two grandmothers and a grandfather, was introduced to the media before working out with the Astros and throwing in the bullpen in front of pitching coach Doug Brocail.
"He's got a lot of talent," Brocail said. "I had him throwing very soft because he hasn't been doing a lot of work, but he was still in the mid 90s. He was probably in the low 90s, but with a lot left to go."
McCullers will report on Tuesday to the Astros' Gulf Coast League affiliate in Kissimmee, Fla. -- where Correa made his professional debut with a single in his first at-bat Monday -- before moving to rookie level Greeneville later in the season. The Astros will closely monitor his innings.
"It's a dream come true," McCullers said. "Every single kid who ever played baseball wants to be at this point right now and beyond in the big leagues and things like that. This is just the first of, hopefully, many steps."
McCullers went 13-0 with a 0.18 ERA and 140 strikeouts in 77 1/3 innings during his senior season at Jesuit High School (Fla.) and the Astros jumped at the chance to take him at No. 41, despite his commitment to play at Florida. He'll join a growing group of impressive young arms in the Astros system, including Jarred Cosart, Mike Foltynewicz and Adrian Houser.
"I was always solid in my commitment to the University of Florida," McCullers said. "It's somewhere I could have seen myself, but an opportunity presented itself that me and my family felt we couldn't walk away from, and I couldn't be more excited to start my pro career."
Agent Scott Boras, who represents McCullers, said he had to be comfortable with the Astros' plans for McCullers before the sides even talked money. Boras said he liked the way Luhnow and the Cardinals developed young talent while Luhnow was running St. Louis' Draft process.
"The great thing is we have a history with Jeff and when he worked with the Cardinals and development of players," Boras said. "He has a real understanding of the metrics and has the coaching staff and the personnel needed to do that. Once those things were brought forward, you're talking about a high school athlete who is really making a commitment, and how he's developed is very important.
"It was very clear at the onset that Lance and his family were very comfortable with the design and plans that Jeff and the Astros have put in place for Lance. Once that dynamic was met, then we had an opportunity for further discussion to resolve the economic aspect of it."
After signing their first two picks, the Astros saved more than $1 million in the bonus pool that can be used to sign other players in the 10 rounds. They're having productive discussions with fourth-round pick Rio Ruiz, a third-baseman from Bishop Amat High School (Calif.) who has committed to USC. Second-round pick Nolan Fontana, a shortstop from Florida, can't be signed until after the College World Series -- one of four Astros Draft picks playing in Omaha.
"We're going to continue to pursue everybody that we can and we still have some flexibility," Luhnow said.
With McCullers in the fold, the Astros have signed 28 of their 41 Draft picks, including 17 players selected in the first 21 rounds. They have until July 13 to negotiate deals with all Draft picks.
"If we called it a day and that was our Draft, we'd be very, very excited," Luhnow said. "But we still have some players playing in the College World Series that we're still in discussions with. We're not going to rest until every penny is spent and every player we can possibly sign is in the fold."