This isn't too surprising. Brocail's velocity seemed to be way down since coming back from his previous DL stint. Cause is listed as "strained shoulder." The Astros are so depleted that it is actually pretty helpful to get Erstad back on the team. Coste was hurting the Astros hitting against RHP, and Erstad will allow the Astros to have a proper platoon at 1st base. Erstad is also a better defensive replacement in the outfield than Michaels.