The Astros designated Montero for assignment Wednesday.
Montero is in the second year of a three-year, $34.5 million contract, and the Astros appear willing to absorb what remains on that deal. The veteran reliever made 41 appearances for Houston this season, posting a 4.70 ERA and 23:19 K:BB over 38.1 innings. Montero will likely pass through waivers unclaimed and will have the ability to elect free agency.