The Mets moved right-hander Jeurys Familia (blood clot in shoulder) to the 60-day disabled list to open up a 40-man roster spot for Ramirez.
Ramirez, 27, will be available for Tuesday night's game in Phoenix against the Diamondbacks.
Seeking another option for their beleaguered bullpen, the Mets signed righthanded reliever Neil Ramirez to a major-league contract on Tuesday. The Blue Jays claimed Ramirez off waivers, but designated him for assignment before he pitched in a game.
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Making nine relief appearances as a member of the Giants bullpen this season, his only action atop the highest level in 2017, Ramirez amassed a whopping 8.71 ERA over the course of 10.1 innings of work. For his big league career, he now owns a 3.72 ERA over the course of 96 regular-season relief appearances and an even 92 innings of work in all. Last year, Ramirez played for the Cubs, Brewers and Twins. In addition, closer Jeurys Familia, who may miss the remainder of the season after having surgery to fix a blood clot in his pitching arm, was moved to the 60-day DL. He is expected to return to the team late this season after having surgery last week for a blocked artery near his right armpit.
The 31-year-old veteran is batting.257 this season with three home runs and 14 RBIs. He tried to play through the injury after an MRI did not show serious damage, but he aggravated it during an at-bat Saturday at Milwaukee. The right-hander is 2-3 with a 7.06 ERA in seven starts and one relief appearance this season.