Alvarez was recalled from Triple-A Round Rock on Friday.
With reliever Tony Barnette landing on the disabled list with a finger issue, the Rangers will summon Alvarez from Round Rock to fill the void. Alvarez's lone appearance in the minors was a scoreless one, which is consistent with his serviceable 3.27 ERA out of the major-league bullpen earlier in the season. He'll likely serve as a middle reliever for now.