Where the Nats' 40-man roster stands on decision day

There's a deadline this afternoon around baseball. It's not one of the major deadlines, like the trade deadline or the qualifying offer deadline. But it's nonetheless a potentially significant one when it comes to organizations keeping their best prospects from getting swooped up by another club.

By 5 p.m. EST, all teams must add any players they wish to protect from being selected in the Rule 5 draft to their 40-man roster.

What does that mean? A quick primer for those who aren't familiar with this process ...

The Rule 5 draft takes place every year on the final day of the Winter Meetings (Dec. 8 this year at the annual event, which is being held here in town at National Harbor). It gives clubs the opportunity to draft away minor leaguers from other franchises who aren't on the 40-man roster but have been professional ballplayers for a certain amount of time.

How much time? Well, any player who signed his first contract before turning 19 is eligible for the Rule 5 draft after five seasons in the minors. And any player who signed his first contract after turning 19 is eligible after four seasons in the minors.

For the most part, that means any players taken in the 2012 draft out of high school or the 2013 draft out of college who aren't on their club's 40-man rosters are unprotected. You also have to add players signed internationally, most notably those from Latin America, who usually are signed before turning 19.

If an unprotected player is selected in the Rule 5 draft, he must remain on his new club's major league roster the entire season or else be offered back to his original club.

So that's how it works. Now, who in the Nationals' farm system is vulnerable this year?

Among the notable players who are eligible for this Rule 5 draft are pitchers Austin Voth, Jake Johansen and Bryan Harper; infielders Matt Skole and Jose Marmolejos; and outfielders Rafael Bautista and Isaac Ballou. Not every one of them is a top prospect, but all have been in the Nationals' farm system for a while without reaching the 40-man roster.

The Nationals won't protect all eight of those players, but they'll likely protect at least a few of them. Voth, who posted a 3.15 ERA in 157 innings at Triple-A Syracuse this season, is highly regarded within the organization and could make his major league debut in 2017. Johansen was the club's second-round pick in the 2013 draft, though his career hasn't taken off yet.

Harper (Bryce's older brother) really made a name for himself this season as a left-handed reliever, with a 2.18 ERA in 40 appearances split between Syracuse and Double-A Harrisburg. Marmolejos was recently named the organizational Player of the Year, with Bautista winning the franchise's annual Bob Boone Award.

Now, where does the Nationals' 40-man roster stand at the moment? It's actually in very good shape, with only 32 players currently listed after a bunch of players became free agents following the World Series.

Here's the full 40-man roster right now ...

PITCHERS (16): A.J. Cole, Lucas Giolito, Koda Glover, Gio Gonzalez, Trevor Gott, Matt Grace, Shawn Kelley, Reynaldo Lopez, Rafael Martin, Oliver Perez, Tanner Roark, Joe Ross, Max Scherzer, Sammy Solis, Stephen Strasburg, Blake Treinen

CATCHERS (3): Spencer Kieboom, Jose Lobaton, Pedro Severino

INFIELDERS (6): Wilmer Difo, Danny Espinosa, Daniel Murphy, Anthony Rendon, Clint Robinson, Ryan Zimmerman

OUTFIELDERS (7): Brian Goodwin, Bryce Harper, Chris Heisey, Ben Revere, Michael A. Taylor, Trea Turner, Jayson Werth

Keep in mind, the Nationals need to keep some slots open for any players they acquire this winter. So they aren't going to protect so many Rule 5-eligible guys that the 40-man roster gets clogged up.