Baseball’s Rule 5 Draft was on Thursday, December 10. What’s a Rule 5 Draft? Matt Nekrich went over it last year. I’ll revisit it here. Not to be a total jerk about it, but it’s hard to explain the Rule 5 Draft (you’ll also see it called the Rule V Draft; the official rules use the Arabic rather than Roman) without explaining the 40-man roster. Can we start with that?

OK, so what’s a 40-Man Roster? Most fans know what a 25-man roster is: Those are the 25 players active in the majors for each team. The 40-man roster (official name: MLB Reserve List) is different. It consists of:

1. The players on a team’s 25-man roster
2. Major league players on the team’s 15-day disabled list or 7-day concussion list
3. Players on the Bereavement List (three to seven days), Family Medical Emergency List (also three to seven days), Paternity List (24-72 hours)
4. Players signed to a major league contract but on an optional assignment to the minors (commonly called optioned to the minors)

The 25-man roster’s pretty self-explanatory, right? Yes, with two exceptions. One, a team can have as few as 24 active players if it wishes. Second, teams can temporarily add a 26th player on any day on which the team is playing a doubleheader. They can add the 26th player for the entire day if the doubleheader was scheduled at least 48 hours in advance. If the doubleheader was scheduled less than 48 hours ahead, the team can add the 26th player for the second game only.

Well, the disabled list is self-explanatory, isn’t it? Yes, as far as the 15-day and 7-day disabled lists go.

What, there’s another disabled list? Yes, the Emergency Disabled List (commonly called the 60-day disabled list). If a player’s put on the 60-day disabled list, his team can move him off the 40-man roster. When you see a player who’s been injured for a long time moved from the 15-day to the 60-day disabled list, there could be a roster management reason behind it. Last year, the Dodgers put pitcher Hyun-Jin Ryu on the 15-day DL on April 5, retroactive to March 27, with a shoulder injury. He was, at that point, still on their 40-man roster. On May 4, they moved him from the 15-day DL to the 60-day DL, freeing up a spot on the 40-man roster, which they filled by getting pitcher Matt West from the Blue Jays for cash.

Players on the 60-day list, obviously, must stay there for at least 60 days. Players on the 60-day DL must be reinstated on the 40-man roster by 5 PM on the fifth day after the last game of the World Series, or the day after the Series ends if the player’s eligible for free agency. This year, for example, the Phillies activated Cliff Lee, who’s a free agent, from their 60-day DL on November 2, the day after the World Series ended. The Rangers waited until November 6, five days after the season ended, to activate Yu Darvish, who’s under contract for 2016, from their 60-day DL.

The Bereavement, Family Medical Emergency, and Paternity lists–please tell me they’re straightforward. They are.

I suppose the minor league assignment stuff is complicated. Yes it is!

How does a minor league player get on a major league roster in the first place? When an amateur player’s signed and placed in the team’s minor leagues, he’s not put on the 40-man roster. However, that lasts only five years (for players signed at age 18 or younger) or four years (for players signed older). After that time has passed, the player must be placed on the 40-man roster. More on this later.

How do options to the minors work? Generally, once a player’s added to the 40-man roster, he can be optioned to the minors as many times as the team wants for three years. The accounting for years is a little convoluted. If, in a given season, a player spends fewer than 20 days in the minors, he’s considered to have not been optioned for the year, regardless of the number of times he was optioned.

Take National League Rookie of the Year Kris Bryant. He was called up by the Cubs on April 17. He didn’t spend 20 days in the minors. So he could, in theory, get optioned to Iowa as many times as the Cubs want during the 2016, 2017, and 2018 seasons, even though he played there for seven games this year. (He’s filed a grievance over his time in the minors, but that’s over eligibility for arbitration and free agency reasons, not for fear of getting optioned to the minors.) Also, a player who has spent less than five full seasons in professional baseball (defined as 90 days on an active major or minor league roster) can be optioned during a fourth year, giving his team another year in which they can option him.

Then what does it mean when I hear that somebody is “out of options?” It means that the three-year clock on sending him to the minors (four years for a few players, as outlined above) has passed. If the team brings the player up after that deadline and wants to subsequently send him to the minors, they must outright the player to the minors. That means the player gets sent to the minors and removed from the 40-man roster, but must clear waivers (also complicated) before he returns to the major league team. Alternatively, the team can designate him for assignment (commonly called DFA, as in, “He was DFAd.”) When a club designates a player for assignment, he’s removed from the 40-man roster and the team has ten days in which it must trade, release, or outright the player to the minors. (There are also rare occasions in which a DFAd player can be returned to the 40-man roster and optioned to the minors, but that’s unusual.) Note that for purposes of both outrighting and DFA-ing, a player with five years of service time in the majors (another complicated topic) has the right to refuse to be outrighted, immediately becoming a free agent, or he can choose to accept the outright but become a free agent at the end of the season.

Enough already. Over 1,000 words on this stuff is plenty for one post. Fair enough. We’ll wrap up the 40-man roster and come back to the Rule 5 Draft next.

Thanks to Ryan Sullivan for editing help.