But first, I want to say how much fun I'm having watching these Twins play baseball. The defense is making some really slick plays, the offense is getting hits, the starting pitching is pitching well and going deeper into games, and the relief pitching is more reliable. Oh, and the winning is fun too. I'm not ready to have them get fitted for rings just yet -- after all, these are the same guys who dug the big hole to begin with. They still have a long way to go, and they still have things to improve upon. But, as I continue to take things day-by-day, I like that there are more good days than bad. They have a big road trip to San Francisco and Milwaukee coming up. I hope they can keep things up.
With all the DL moves the Twins have had to make this year, the whole moving-guys-off-and-on-rosters-and-DL-lists thing has been quite confusing. I thought I'd try my best to sort things out.
Teams have two rosters -- the 25-man and the 40-man. The 25-man roster is the active roster; these are the guys who suit up for games every day. You can find the Twins current 25-man roster here.
The 40-man roster includes the 25-man roster, plus 15 minor league players who are kind of "on call." These 15 guys are the most likely to be called up if someone on the active roster gets hurt or struggles. This is the Twins current 40-man roster.
There are three versions of the DL a team may use if a player gets hurt: 7-day concussion DL, 15-day DL, and the 60-day DL. These indicate the minimum number of days a player must be inactive. However, if a player gets hurt and waits a couple of days to see if he'll get better but doesn't, he can be placed on the appropriate list retroactive to the day after he last played. The player may come back to action as soon as he is eligible, but he may be out longer.
The 7-day concussion DL is new to Major League Baseball this year. They implemented it to encourage teams to make the player inactive at the first hint of a brain injury and still allowing them to call up a minor leaguer to help the team.
Disabled List Transactions
A player gets hurt and the manager decides that he's no help to the team in his condition, so he places him on the appropriate DL. This takes him off the 25-man roster. If the injury is long-term, and the team has to place him on the 60-day DL, this also takes him off the 40-man roster. Teams generally avoid doing implementing the 60-day DL until the timeline for the player's return is clearly close to 60 days anyway or he's out for the season.
Once the hurt player is on the DL, the team decides which minor league player on the 40-man roster to call up, and he's in the bigs. When the injured player returns (or if the team decides it wants someone else instead), it options him back to the team he came from. If he comes back to the bigs again, he's recalled, and then back down again, he's reassigned. (Although teams sometimes list the second, third, etc., transaction as optioned as well, but "options" are really a year-by-year thing, not a transaction-by-transaction thing. A team uses one player option per year regardless of how many times it calls him up and sends him back to the minors.)
If the team decides to call up a player who isn't currently on the 40-man roster, it has to make some moves to add him. If this is the player's first time with the bigs, the team must purchase his contract. However, someone must be removed from the 40-man to make room. Many times, if there's an injured player who will clearly be out 60 days, it'll just move that guy to the 60-day DL.
A team may decide to remove someone from the 40-man roster for any reason. To do this, it designates him for assignment, after which it has 10 days to decide whether to expose him to waivers, trade him, or release him. If he is placed on waivers, other teams have an opportunity to claim his contract. If he clears waivers, he is then outrighted to the minor league team. A team may only DFA a player once in his career without his consent, and players who have at least five years of service time may not be DFA'd without consent.
If the team choses to release a player, he still must clear waivers, but then he is a free-agent and may sign with another team.
If you want to know more about free agency and all that other stuff, I wrote it up last fall here.
Also, Major League Baseball and the Players Association are currently hammering out a new collective bargaining agreement, so the nuances of these rules are subject to change.