Rehabilitation (Rehab) Assignments

Players on the disabled list (DL) can be sent to the minor leagues for rehab work, typically for one or two weeks. Players are often sent to minor league clubs based on geography and facilities, not necessarily by class for these reassignments.

Class System Variations

The classification system today is a very rough rule of thumb, particularly in the "readiness" category. There are players who start at all levels of the farm system, although launching from Triple-A is the rarest. In recent years, some teams have been known to promote players from Class AA directly to the majors without time in Class AAA. Triple-A has two appropriate nicknames: It's been dubbed the "parking lot" by some sports writers because players can easily get trapped into being reserves for injured major league players. It's also been called the "third major league," because the level of play is exceptional, players play harder because they want to prove something to those judging their talent, and because some teams used to draw as well as, if not better than, their major league counterparts. New stadiums and franchise relocation have made this scenario less likely. The independent leagues also play a role, draining off some talent looking for a change, while some players, particularly ones originally from countries other than the United States, and may elect to play in Japan.

Arizona Fall League is an off-season league owned and operated by Major League Baseball, which operates during the fall in Arizona, United States, at six spring training complexes and attracts many of the top prospects in minor league baseball.

The Australian Baseball League (ABL), jointly owned by Major League Baseball (75%) and the Australian Baseball Federation (25%), is a professional baseball league in Australia. The league is governed by the Australian Baseball Federation (ABF), and is jointly funded by the ABF, Major League Baseball (MLB) and the Australian Federal Government. It uses the same name as a now defunct competition held during the 1990s, and though it shares some history of the original league with the Claxton Shield awarded to winners of both competitions, it is considered to be a separate competition. Because the ABL's season takes place from November through February, the ABL has several players who also play in the minor leagues in North America, making it a winter league, although it is summer in Australia when the season takes place.

The Colombian Professional Baseball League (sponsored by Major League Baseball), also known as the Colombian Winter League, is a professional baseball league based in Colombia. It is a winter league that plays during three months during the Major League Baseball offseason.

The Dominican Republic Professional Baseball League is a winter professional baseball league consisting of six teams spread across the Dominican Republic; it is the top baseball league in that country. The league's players include many from Major League Baseball, and the Dominican league's champion plays each year in the Caribbean Series. Each team plays a fifty-game round-robin schedule that begins at the middle of October and runs to the end of December. The top four teams engage in another round-robin schedule with 18 games per team from the end of December to the end of January; the top two teams in those standings then play a best-of-nine series for the national title. The league's champion advances to the Caribbean Series to play against the representatives from Mexico, Venezuela, and Puerto Rico.

The Mexican Pacific League is a winter minor baseball league in Mexico. The eight-team league's regular season runs from October to December and is followed by a playoff series in January to determine the league champion. The league's winner takes part in the Caribbean Series each year.

The Liga de Béisbol Profesional Roberto Clemente, formerly known as Liga de Béisbol Profesional de Puerto Rico (lit. "Professional Baseball League of Puerto Rico" or LBPPR) and Puerto Rico Baseball League, is the main professional baseball league in Puerto Rico. In 2007, the LBPPR suspended operations for the first time since its creation. In 2008, the organization resumed operations, after restructuring. These included renaming the league to "Puerto Rico Baseball League" and establishing a website. In May 2012, the league debut its current name, choosing to honor Hall of Famer Roberto Clemente by naming it after him and adopting his philosophy of athletic development. Currently consisting of six teams, the league's champion participates in the Caribbean Series.

The Venezuelan Professional Baseball League or Liga Venezolana de Béisbol Profesional (LVBP) is the highest level baseball league in Venezuela.