NEW YORK -- Like most teams, the Mets did some 40-man roster shuffling on Wednesday to protect players from the Rule 5 Draft. Most pertinently, they added four prospects -- infielder Andrés Giménez, catcher Ali Sanchez, and pitchers Thomas Szapucki and Jordan Humphreys -- while designating pitcher Drew Gagnon for assignment. Here’s a look at the process and the Mets’ decisions:

What was the purpose of Wednesday’s deadline?
Each year, the Rule 5 Draft allows teams to poach players who have reached certain age thresholds from other organizations. Prospects signed at age 18 or younger become Rule 5-eligible once they have been in their organizations for five seasons. Those signed at age 19 or older become eligible after four seasons. However, teams always have the option to protect those players by placing them on their 40-man rosters. Wednesday was the deadline to do so.

Whom did the Mets protect?
The Mets’ most obvious 40-man add was their third-ranked prospect, Giménez, who hit only .250/.309/.387 at Double-A Binghamton last year but is rapidly becoming Major League-ready. Giménez, who won the batting title in the Arizona Fall League, remains one of baseball’s most promising middle-infield prospects.

Also on the Mets’ list was Szapucki, their 12th-ranked prospect according to MLB Pipeline. A former fifth-round Draft pick, Szapucki missed all of 2018 due to Tommy John surgery, but he returned last summer to throw 61 2/3 effective innings over three Minor League levels, making it all the way to Binghamton. Although Szapucki isn’t likely to make the Majors until 2021, teams are often tempted to gamble on his breed of talent in the Rule 5 Draft.

Sanchez is a defensive-minded catcher who posted a .648 OPS in the upper Minors this year. He made it all the way to Triple-A Syracuse and has a chance to play in the Majors next season. He’s 17th on the Mets’ prospect list.

Humphreys, another Tommy John alumnus, returned to throw two innings in Rookie ball. He’s the Mets’ 22nd-ranked prospect.

Whom did the team leave exposed? And why?
The Mets left four of their Top 30 prospects unprotected: eighth-ranked shortstop Shervyen Newton, 27th-ranked catcher Patrick Mazeika, 28th-ranked outfielder Desmond Lindsay and 29th-ranked infielder Luis Carpio.

Although Newton ranks highest on the list, he’s just 20 years old and coming off a year in which he hit .209/.283/.330 at Class A Columbia. As such, it’s unlikely another club would consider rostering him for a full big league season. Carpio is a different story. He’s already 22 and coming off a reasonably successful half-year at Binghamton. It’s possible a team in search of bench help might take a look at him.

Were there any surprises?
Humphreys was no lock to be protected, considering he’s a former 18th-round Draft pick who has pitched just two regular-season innings since Tommy John surgery in 2017. But the Mets may have convinced themselves based upon his Arizona Fall League performance last month: a 0.77 ERA over 11 2/3 innings. They also had an extra opening after designating Gagnon for assignment.

What about their other top prospects?
No worries there. Guys like Brett Baty and Matthew Allan aren’t eligible for the Rule 5 Draft because they haven’t been in the organization for four-plus seasons. The Mets won’t have to protect them for several years to come.

What now?
The Rule 5 Draft is scheduled for Dec. 12 during the Winter Meetings in San Diego. To draft a prospect left exposed, teams must pay a $100,000 fee. If they don’t keep that player for the entire season, they must offer him back to his original team for $50,000. So even if the Mets lose a player, they won’t necessarily lose him for good.