The trade means the Astros will open the season with Jason Castro and Chris Snyder as their two catchers.
When asked about the player to be named, Astros general manager Jeff Luhnow wouldn't divulge specifics, but it's clear the incoming player will be an important piece to completing the trade.
"I can't really disclose when we're going to do it, but all I can really say on that is the player to be named later is a key component to this deal," Luhnow said.
Chapman, 24, was selected by the Royals in the fourth round of the 2010 Draft out of Florida. He struck out 50 batters in 39 2/3 innings last year at Northwest Arkansas of the Texas League after beginning the season at Class A Wilmington, where he struck out 40 batters in 22 1/3 innings.
Chapman missed the 2008 season at Florida after Tommy John surgery, but by '10, he was arguably the best college reliever in the game. Even though he has the repertoire to start, he's earmarked for the bullpen and reached Double-A in his first full season. He was ranked by MLB.com on the Royals Top 20 Prospects list.
"He's a prospect for us, and he's adding to our organizational depth at the Minor League level," Luhnow said. "I don't know if he's a Double-A or Triple-A guy this year, but he's not Major League-ready. He's a guy, down the road, who could be an elite left-handed pitcher, and that's a valuable commodity to have."
Bourgeois, 30, appeared in 93 games last year for the Astros, hitting .294 with 16 RBIs and 31 stolen bases. He was considered one of the favorites for the backup outfielder role, but the Astros added depth in that department in the offseason by bringing in Travis Buck, Jack Cust and Fernando Martinez, among others.
Bourgeois is a career .262 hitter with 46 stolen bases in 192 career Major League games with the White Sox and Astros, who claimed him off waivers in 2009. The Royals will be his seventh organization.
"It's bittersweet," Bourgeois said. "You always want to have a uniform on. I'm going to another organization, and I'm glad somebody wants me."
Quintero, 32, is a hard-nosed backup catcher who has been with the club since 2005, the second-longest tenure on the team outside of Wandy Rodriguez. The strong-armed Quintero has spent parts of nine seasons in the big leagues, and last year, he started 73 games at catcher when Castro was lost for the season with a knee injury.
"I got my house and everything in Houston, and I'm going to miss everybody here," said Quintero, who will make $1 million this year. "Baseball is baseball, and I'm going to go someplace else I get more opportunity to play."
With Castro missing all of last year following knee surgery and undergoing foot surgery in December, the Astros signed Snyder off the free-agent market to add some depth at catcher.
Quintero was bothered by a bulging disk in his back early in the spring, but the Royals had been scouting him for days as they searched for a replacement for the injured Sal Perez. Quintero is a career .234 hitter with 15 homers and 94 RBIs in 379 career games.
"Jason and Humberto were a big part of this team last year, and both will be missed," Luhnow said. "They are quality players and well-liked in Houston."