Alvarez, who is expected to report to Triple-A Lehigh Valley this week, has not pitched in the big leagues since 2015, when he went 0-4 with a 6.45 ERA in four starts for the Marlins. The 27-year-old was an All-Star with Miami in 2014, going 12-7 with a 2.65 ERA in 30 starts.
The Venezuelan hurler has battled a number of arm injuries over the past two years. He underwent two surgeries on his pitching shoulder during the 2016 season after attempting a comeback with the Athletics organization.
Alvarez, who began his Major League career with Toronto, is 27-34 with a 3.80 ERA in 92 career starts over five big league seasons split between the Blue Jays and Marlins.