The Astros promoted Alvarez to Triple-A Fresno on Friday, Chandler Rome of the Houston Chronicle reports.
Alvarez slashed .325/.389/.615 with 12 home runs in his first season at the Double-A level this year, which made for a short stay at Corpus Christi. The 21-year-old will likely join Fresno's outfield rotation for the rest of the season if he illustrates he can hold his own against superior competition.