According to the BA transactions page, the Astros released a bunch of guys who had been in EST: RHP Jay Gause, RHP Juan Hernandez, RHP Krishawn Holley, RHP Gerardo Ramirez, LHP Christian Perdomo, C Hayden Timberlake.
Timberlake was signed in 2013 out of Australia and played last year in the DSL. Holley was a 39th rounder from back in 2010 who never rose above Tri-City in his 5 years in the system. Perdomo was a guy signed by the Red Sox out of (I kid you not) Advanced Software Analysis Junior College as a NDFA. Released by Boston after one year in the GCL, the Astros picked him up and after a second unsuccessful season in the GCL is now looking for a third organization to join. Hernandez was signed in 2011 as an intl FA out of the DR and his 3 years in the org were all spent in the DSL (excluding 3 GCL games). Ramirez was on his second organization after being signed out of Mexico by the Twins and released after 2 seasons. The Astros picked him up in 2013 where he pitched at Greeneville.
Perhaps the most surprising of the releases would be Gause. He came in last year's draft in the 10th round. While the numbers in a handful of appearances in the NY-P were fairly awful, such a quick hook after just one season is a bit odd for someone drafted (relatively) high. A swing and miss for the scouting staff.
ETA:
Actually, looking into it more, Gause was a college senior whose underslot sign at $65K contributed nearly $80K to the overall bonus pool so his being taken in the 10th round was more than just a function of talent level.