Alvarez has been working out at first base, Chandler Rome of the Houston Chronicle reports.
Houston manager Dusty Baker said Alvarez "is not yet ready" to start a game there, but if he could provide competent defense there, it would improve the manager's ability to manage the roster. The Astros are currently missing Yuli Gurriel (neck), which leaves them a player short. Additionally, the team could use Alvarez at first base in National League cities.