den Dekker roster beginning Monday, a source told ESPNNewYork.com.
EY Jr., who turned 29 on Sunday, is expected to land on the disabled list with a pulled hamstring. He went unused in the first game of Sunday's doubleheader.
Den Dekker is hitting .269 with four homers and 26 RBIs in 171 at-bats with Triple-A Las Vegas.
Once Travis d'Arnaud is activated from the disabled list later this week, the Mets should become the first team in MLB history with three players with lower-case "D" surnames on the roster. The other: Jacob deGrom.