With the Mets roster at 39 players and them signing two pitchers, someone needed to designated for assignment. I expected the first player to go to be Luis Hernandez and if a second player was to be cut I thought Tobi Stoner would be a good candidate.
Igarashi posted a 1.35 ERA before his injury and never seemed to recover, however; the organization believed that he may have needed a heavier workload as he was accustom to in Japan ( source ESPN NY ). Terry Collins who managed in Japan for two seasons should have been the perfect candidate to manage him.
With the state of the pen and his history as a closer I thought he would be at least kept around to see what he could offer in the first half of the season.
But as Adam Rubin pointed out, designating him for assignment doesn't mean he isn't in the Mets plans and it made sense to make this move. Iggy is owed 1.75MM for the season and it will be surprising if someone claims him after posting 7.12 ERA. If someone claims him the Mets are off the hook for his bloated salary and if he makes it through waivers he wont file for free agency because he certainly won't get what the Mets are obligated to pay him.
While it came as a surprise, the move actually makes sense and is a safe move for the organization.
Assuming Ryota Igarashi clears waivers, which should be the case given salary, he's expected in major league camp as a non-roster invitee. source Adam Rubin