The Mets selected Severino's contract from Triple-A Syracuse and optioned him to Syracuse on Tuesday.
Severino likely had an opt-out clause in his minor-league contract, and the Mets have added him to the 40-man roster to prevent him from exercising it. He's posted a 1.04 ERA and 18:8 K:BB over 17.1 innings with Syracuse this season and could get a look the next time the Mets need a left-handed reliever.