Yamamoto was re-assigned to the Mets' minor-league camp Friday, Joe Trezza of MLB.com reports.
The right-hander wasn't expected to break camp on the big-league roster anyway, but the quick exile is likely due to the shortened spring training schedule and a lack of innings for the Mets' established arms. "We need to get him stretched out," manager Buck Showalter said regarding Yamamoto's demotion. The 25-year-old should begin the year at Triple-A Syracuse and could see action in the majors later this summer if injuries force the Mets to dip into their rotation depth.