On the same day the Phillies signed an 18-year-old outfielder they think can be a star big-league player, they lost a 19-year-old outfielder with that same potential.

The player they signed was Larry Greene, the 39th overall pick in the compensatory round of this year's draft. With a midnight deadline looming Monday, the Phillies agreed to a $1 million signing bonus with Greene, according to Baseball America.

The player the Phillies lost was single-A Lakewood outfielder Domingo Santana, who was assigned to the Houston Astros to complete the trade-deadline deal that placed rightfielder Hunter Pence in the middle of manager Charlie Manuel's lineup.

Greene, the Phillies' first selection in the draft, hit .562 and slugged 18 home runs in his senior season at Berrien High School in Georgia. The left-handed hitting and right-handed throwing Greene is 6-foot-2 and 235 pounds. At one time he drew interest from the University of Alabama as a football player, but he declared his allegiance for baseball before his senior year.

A baseball source also indicated that the team believed it would strike a deal with second-round pick Roman Quinn before the midnight deadline. Quinn, a shortstop from Port St. Joseph High School in the Florida panhandle, took batting practice with the Phillies last month.

The Phillies did not officially announce Greene's signing, but they did announce the completion of the Pence deal by sending Santana to the Astros. He was the fourth minor-leaguer acquired by the Astros, joining pitchers Jared Cosart and Josh Zeid and first baseman Jonathan Singleton.

Santana, who just turned 19 earlier this month, was hitting .269 with 29 doubles, four triples, seven home runs and 32 RBIs at Lakewood.

A National League scout who watched Cosart, Singleton and Santana play this season said he believed Singleton was the only one with true star potential.

"He's going to be the player of that group," the scout said. "He's going to be a great player."

Singleton batted .339 with five doubles, two home runs and six RBIs in his first 14 games at single-A Lancaster in the California League, while Cosart was 0-1 with a 4.70 ERA in his first three starts with Houston's double-A Corpus Christi affiliate.

"I still think Cosart might be a guy who pitches out of the bullpen rather than as a starter," the scout said.

And what about Santana?

"I think he has a lot of growing up to do," the scout said. "But he just turned 19, so it's definitely worth that chance. He's 6-foot-4 with a plus arm and the ball jumps off his bat in batting practice."

It will be interesting to see how the prospects the Astros acquired from the Phillies perform in the future. Of course, we will know in a few months if Pence was the piece that pushed the Phillies to the promised land.

Extra bases. The Phillies made it official that they have signed pitcher Dave Bush to a minor-league contract. Bush, 31, will report to the Phillies' triple-A Lehigh Valley squad this week. The Conestoga High product has a career major-league record of 46-69 with a 4.70 ERA.

Contact staff writer Bob Brookover at bbrookover@phillynews.com or @brookob on Twitter.