Houston had previously received outfielder Jonathan Singleton and pitchers Jarred Cosart and Josh Zeid in the deal. Singleton and Cosart had been considered the top prospects in the Phillies' system.
The 19-year-old Santana, ranked as Philadelphia's No. 9 prospect by Baseball America, was hitting .269 with seven homers in 96 games for Single-A Lakewood this season. He will be assigned to Houston's Class-A affiliate in Lexington.