Yamamoto was traded from the Marlins to the Mets in exchange for Federico Polanco on Monday, Tim Healey of Newsday reports.
Yamamoto moves to a division rival after being designated for assignment on Thursday. Through 90 career innings at the highest level, his 6.20 ERA doesn't look particularly promising, with his poor 11.0 percent walk rate and 35.3 percent groundball rate offsetting a decent 24.2 percent strikeout rate. He's still just 24 years old, though, so there's still time for him to develop into a backend starter.