The New York Mets’ 40-man roster has four open spots at the moment, but there’s not much reason to expect they’ll add any of their prospects eligible for the Rule 5 draft before today’s deadline. Clubs are required to finalize their 40-man rosters on November 20 ahead of the Rule 5 draft.
If a player has enough years of professional experience to be eligible and is not placed on the 40-man roster, he could be taken by another team when that draft happens on December 10. To take a player, a club has to be willing to keep that player on its active roster for the entire season, with a 90-day minimum to ensure clubs don’t simply take a player and then stash them on the injured list.