Diaz will pitch for Team Puerto Rico in this year's World Baseball Classic, Greg Johns of MLB.com reports.
The 22-year-old right-hander heads into the 2017 campaign as the Mariners closer after tallying 18 saves in 21 chances last season, along with an 88:15 K:BB and 2.79 ERA over 49 appearances. Diaz will join a Team Puerto Rico pitching staff that includes Twins hurlers Hector Santiago and Jose Berrios and the Mets' Seth Lugo.