Ramirez, 24, missed all of last season after undergoing right shoulder surgery, allowing the Nationals to keep him on their roster throughout the summer. Come season's end, Washington followed Rule 5 protocol in offering Ramirez back to his former team for $25,000, half the price the Nats originally paid for him.
Splitting time with Class A St. Lucie and Double-A Binghamton in 2010, Ramirez finished 4-4 with a 4.16 ERA, showcasing a fastball clocked as high as 100 mph.
The Mets kept one of their two selections in last year's Rule 5 Draft, offering second baseman Brad Emaus back to the Blue Jays and keeping right-hander Pedro Beato from the Orioles.
Beato became one of the rare Rule 5 Draft picks to stick with his new club, posting a 4.30 ERA over 60 appearances with the Mets. He remains a bullpen candidate for next season.
Baseball's annual Rule 5 Draft allows teams to scoop unprotected Minor League veterans away from other organizations, under the stipulation that they must stay on the big league roster or disabled list all season or be offered back to their original club.