Noah Syndergaard headlines the newest additions to the Mets' 40-man roster.NEW YORK -- The Mets added right-handers Noah Syndergaard, Cory Mazzoni, Hansel Robles, Gabriel Ynoa and Akeel Morris and left-hander Jack Leathersich to the 40-man roster in order to shield them from Rule 5 draft eligibility.

Right-handed reliever Jeff Walters, who was added to the roster a year ago, cleared waivers and was removed. He was outrighted to Triple-A Las Vegas. Walters underwent Tommy John surgery last June 17 and presumably will not be ready to contribute until the summer.

The Mets' 40-man roster is full.

Among the players left exposed and eligible to be taken at the Rule 5 draft on Dec. 11: right-handers Logan Verrett, Tyler Pill and Darwin Frias, outfielder/third baseman Dustin Lawley and infielder T.J. Rivera.

Syndergaard, 22, went 9-7 with a 4.60 ERA and 145 strikeouts in 26 starts for Las Vegas.

Mazzoni, 25, went a combined 7-2 with a 4.68 ERA in 14 starts with four teams. He missed the opening two months after suffering a lat-muscle strain in the final Grapefruit League game.

Robles, 24, went 7-6 with a 4.31 ERA in 30 appearances (18 starts) with Binghamton.

Ynoa, 21, went a combined 11-4 with a 4.07 ERA in 25 starts for Binghamton and St. Lucie.

Morris, 22, went 4-1 with a 0.63 ERA and 16 saves in 41 relief appearances with Savannah.

Leathersich, 24, had 48 relief appearances with Las Vegas and Binghamton. He went a combined 3-3 with a 3.31 ERA. For his career, Leathersich has 334 strikeouts in 197 1/3 innings.