NEW YORK -- The Mets left one of their top defensive prospects exposed to the Rule 5 Draft on Tuesday, as they did not make any 40-man roster adds prior to the deadline.

The team chose not to protect outfielder Jake Mangum, who is eligible for the Rule 5 Draft for the first time. Mangum, the club’s fourth-round selection in the 2019 MLB Draft, was limited to 72 games this season due to a stress reaction in his spine. He is considered old for a prospect at 26 years old and does not rank among MLB Pipeline’s Top 30 Mets prospects. But he is widely considered one of the organization’s best defensive players at any position, which could entice rival teams.

The Rule 5 Draft is scheduled for Dec. 7 at the Winter Meetings in San Diego. Players who signed their first professional contract at age 18 or younger must be added to 40-man rosters within five seasons or they become eligible to be drafted by other organizations through the Rule 5 process. Players signed at 19 or older must be protected within four seasons. Clubs pay $100,000 to select a player in the Major League phase of the Rule 5 Draft. If that player doesn’t stay on the 25-man roster for the full season, he must be offered back to his former team for $50,000.

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The Mets already had added three of the players they were likely to protect: third baseman Brett Baty, catcher Francisco Álvarez and pitcher Bryce Montes de Oca, all of whom made the roster in the second half of the season. That left a relatively shallow pool for the team to consider, including Mangum, outfielder Stanley Consuegra and right-hander Dedniel Núñez.

Although Consuegra -- ranked as the Mets' No. 23 prospect by MLB Pipeline -- is higher rated than Mangum, he is 22 years old with no experience above Class A ball, which makes him less likely to be drafted. Mangum, by contrast, is a former Mississippi State star who has played in 144 games in the upper Minors. Should he go unclaimed in the Rule 5 Draft, Mangum would have a strong chance to make New York’s Opening Day roster as a reserve outfielder. But another team could take a chance on Mangum, a dynamic center fielder who holds MSU’s career hits record.

The Mets have eight openings on their 40-man roster, but they will need to use several of those on pitchers to fill out their staff.