Diaz fanned two batters in a perfect ninth inning during Monday's 5-1 win over the Phillies.
Diaz was called on to protect a four-run lead and locked it down despite it not being a save situation. The 25-year-old has 16 strikeouts and a 1.04 ERA in 8.2 innings of work. He's also a perfect 7-for-7 in save chances in his first year with the Mets.