Barring trades, Ken Giles, Will Harris and Chris Devenski will return. Joe Musgrove could be an option as well if the Astros decide to make him a full-time reliever. This is a solid group, but clearly not quite enough.
Luke Gregerson, Francisco Liriano, and Tyler Clippard are free agents and probably won’t return. Tony Sipp is still under contract for next season, but you can’t count on getting any useful innings from him. Gregerson’s $6.25 million salary is coming off the books, as well as Carlos Beltran’s $16 million deal.