Minor League Affiliation Explained: Player Development Contracts
How a minor league team becomes the affiliate of a major league club: parent clubs, player development contracts and licenses, who pays whom, how players move between levels and how the 2021 overhaul changed the map.
When you watch a minor league game, the players wear the name of the town on their chests, but most of them belong to someone else. Each player is under contract to a major league club, called the parent club, which signed him, pays his salary and decides which level he plays at. The local team that wears the town's name is the affiliate, and its job is to put on the games, run the ballpark and give the parent club a place to develop its players. The agreement that joins the two is what this article explains.
The arrangement has a long history and changed sharply in 2021, when Major League Baseball took direct control of the minors and cut the number of affiliated clubs. Understanding both the old and the new system explains why a club's Triple-A team can be hundreds of miles from the major league park, why a good hitter can disappear from a lineup overnight, and why an affiliation changing hands can be front-page news in a small city. This is a general guide; contract terms change with each labor agreement, so check MLB's own materials for the current details.
The basic idea: who owns what
In the affiliated system, a minor league club and a major league club each have a role.
- The parent club signs the players, owns their contracts, pays their salaries, and supplies the manager, coaches, trainers and other uniformed staff. It decides who plays where and who moves up or down.
- The affiliate provides the ballpark, runs the business side (tickets, concessions, promotions, local sponsors, marketing), handles local operations and staffs the front office.
That division is the heart of the arrangement. The town gets baseball and a local business; the major league club gets a place to develop talent that it does not have to own outright or build in a city of its own. The players are not employees of the affiliate, which is why a prospect can be promoted from one level to the next in a single day without anyone in the local front office having a say.
How the system began
Until the 1920s, minor league clubs were mostly independent businesses that developed their own players and sold them to major league teams for cash. The model changed when the St. Louis Cardinals, under their executive Branch Rickey, began buying or controlling minor league clubs in order to have a supply of young players. The idea of the chain, or "farm system," spread through the sport in the following decades, and by the middle of the century most minor league clubs were tied to a major league parent in one way or another.
Over time the relationship was formalized in agreements between Major League Baseball and the organization of minor leagues. The standard form for many decades was the player development contract, or PDC, a document between one major league club and one minor league club. It spelled out the duties above, set a term (commonly two or four years) and could be renewed or allowed to lapse. When a PDC ended, either side could look for a new partner, which is why affiliations changed hands and why a minor league town could lose its team to a rival city that made a better offer.
All the PDCs sat under a larger framework, the Professional Baseball Agreement, which was renegotiated periodically between MLB and the minor leagues' governing body. It set the broad rules of the minors, including how many teams could be affiliated, the levels, and the minimum standards for ballparks.
The 2021 overhaul
The Professional Baseball Agreement expired after the 2020 season, a season in which the pandemic canceled minor league play altogether. Instead of renewing it, Major League Baseball took over the operation of the affiliated minors and announced a new structure. Before the change, roughly 160 clubs in the United States and Canada held affiliations; after it, 120 clubs at the four full-season levels did. Communities that lost their affiliation could continue as independent teams, join a new college-age draft league, or in some cases lose professional baseball altogether.
The most important legal change was the move from the old contract to a player development license, or PDL. Instead of a series of short agreements with each parent club, the 120 licensed clubs signed ten-year licenses with Major League Baseball. The licenses set standards for facilities, such as locker rooms, lighting and training space, and tied the club into a system MLB controls directly.
The new map is simpler than the old one. Each major league club has exactly four full-season affiliates, one at each level.
| Level | What it is | Affiliates per MLB club |
|---|---|---|
| Triple-A | The top minor league level, one step from the majors | 1 |
| Double-A | The level where many prospects face their first serious test | 1 |
| High-A | A full-season level for developing players | 1 |
| Single-A | The lowest full-season level | 1 |
| Complex league | Short-season, in Florida and Arizona, for new signees and rehabilitating players | 1 or more |
| Dominican Summer League | Short-season, for international signees | 1 or more |
The Triple-A circuits were renamed for a time as Triple-A East and Triple-A West, and the older names, International League and Pacific Coast League, returned in 2022. The history of those two leagues, which run back more than a century, is in the Pacific Coast League and the International League.
What a system looks like
As an example of how an organization is spread across a map, the Toronto Blue Jays' affiliates as of the 2025 season included Buffalo at Triple-A, New Hampshire at Double-A, Vancouver at High-A and Dunedin at Single-A. Those four towns are spread from Florida to British Columbia; the club's farm system is a network, not a neighborhood. Affiliates change, so check the club's own listing for the current partners. The history of the Blue Jays themselves, including how an expansion franchise built its system, is in the Toronto Blue Jays franchise history.
Geography matters to clubs. A Triple-A team close to the parent can supply emergency replacements by car the same day. A team in a far city has the advantage of a market with no competing major league club. One of the stated goals of the 2021 realignment was to place affiliates closer to their parent clubs, a goal that is not always reachable.
How a player moves through the system
A hypothetical player shows how the contracts work. Suppose a high school pitcher is chosen in the amateur draft. He signs with the club that picked him, not with any affiliate, and the club assigns him to a level. A new signee often begins in a complex league in Florida or Arizona, where the games are played in small stadiums with few fans and the aim is instruction. If he develops, the club promotes him to Single-A, then to High-A, Double-A and Triple-A. The pace is the parent's call: some players move one level a season, some skip a level, some spend years at the same stop.
The parent club also decides when the player's progress should be protected or tested. Three rules shape those decisions.
- The 40-man roster. A club's 40-man roster consists of players under contract to the major league organization, including those assigned to the minors. Putting a player on it protects him from being taken by another club in the Rule 5 draft, and it also starts the clock on his options.
- Options. A player on the 40-man roster can be sent to the minors, or "optioned," without being exposed to other teams, but only for a limited number of seasons. When a player runs out of options, the club must keep him on the major league roster or expose him to waivers.
- Minor league free agency. A player who has spent enough seasons in the minors without being added to the 40-man roster can become a free agent and sign with any club.
The Rule 5 draft, held each winter, lets other clubs claim certain unprotected players, a safeguard against a team hoarding talent in its farm system. The drafts that fill the system in the first place are covered in the history of the amateur draft and signing bonuses and in the first amateur draft of 1965.
The major league roster is a limited number of players, and the minors are where the rest wait. An injured major leaguer may also be sent on a rehab assignment to an affiliate for a limited number of days to regain form, which is why a famous name can appear in a small park for a few games.
What changed for the players
For decades minor league players were paid poorly. The pay was set by the parent club and by MLB rules, and many players lived on small salaries for years. After a series of lawsuits and organizing efforts, minor league players joined the Major League Baseball Players Association in 2022, and a first collective bargaining agreement for them took effect in 2023, setting minimum salaries and other terms. The details are in the agreement itself and on the union's and MLB's websites; this article does not quote salary figures.
The change matters to the affiliation system because it moved a long-standing question, what minor leaguers are paid and under what conditions, from custom into a negotiated agreement. The parent club is the employer, and the affiliate is not.
Why affiliation matters to fans
For a fan in a minor league city, the affiliation is why the lineup changes. A player who is hitting well in Double-A may be gone to Triple-A in the middle of a series. An injured major leaguer may appear for three games and vanish. A pitcher may be limited to a set number of innings because the parent club wants to protect his arm, even if the local fans would like to see him finish a game. The team in the stands is a real club with a real history, and it is also a part of a larger organization whose priorities are not the local standings.
The reverse is also true. Because the parent club pays the players and the staff, a strong local business can make the affiliate profitable at modest prices, and a minor league park is often one of the least expensive ways to see professional baseball. For more on that side of the sport, read minor league ballparks and the fan experience.
The tests MLB runs in the minors
Because MLB now controls the structure, it also uses the affiliated minors as a testing ground for rules. Ideas such as pitch timers, limits on defensive shifts, larger bases and automated ball-and-strike systems were tried at minor league levels, and several of them, including the pitch timer, larger bases and limits on shifts, reached the majors in 2023. The full list and what the results taught MLB is in what minor league rule experiments taught MLB. The affiliation system is what makes that possible: the parent clubs have to agree to the experiments, and the affiliates, under their licenses, play by whatever rules MLB sets.
Outside the system
Not every professional club is affiliated. Independent leagues, such as the Atlantic League, operate without a parent club and sign their own players, who may be released from a contract if a major league organization buys it. The independent leagues article covers that world. In 2021, MLB also created a Draft League for college-age players and others on a summer schedule, which is separate from the affiliated levels.
A short glossary for reading transaction lists
Transaction lists use a shorthand that makes sense once you know who owns what. Each of these terms describes a move between the parent club and its affiliates.
| Term | What it means |
|---|---|
| Recalled or called up | The parent club brings a player from an affiliate to the major league roster. |
| Optioned | The parent club sends a player on its 40-man roster to an affiliate, keeping the right to recall him. |
| Assigned | A player not on the 40-man roster is placed with a particular affiliate. |
| Rehab assignment | An injured major leaguer plays for an affiliate for a limited number of days before returning. |
| Designated for assignment | The club removes a player from the 40-man roster and has a short window to trade him or place him on waivers. |
| Released | The club ends the player's contract. |
| Minor league free agent | A player whose minor league contract has run out and who can sign with any club. |
When a Triple-A player is recalled, no one at the affiliate approves the move. That is not a flaw in the system; it is the system. The affiliate's loss is the parent club's gain, and the next player up from a lower level fills the vacancy. A single call-up can start a chain of moves that reaches all the way down to the complex league. You can follow current moves on the site's transactions page.
Choosing an affiliate also involves more than distance. A parent club looks at the quality of the ballpark and training facilities, the length of the license and the local market, the climate (a warm-weather affiliate lets players work outdoors earlier in the spring), the quality of the local front office, and whether the community will support a team. A town considers the same questions in reverse: whether the parent club is a good partner, whether its prospects will draw fans, and whether the license terms are affordable. Both sides are making a long-term decision, which is why announcements of a new affiliation are treated as news.
Common questions
Who pays the minor league players? The parent club, which holds their contracts. The affiliate pays for the ballpark and its own staff.
Can a team change affiliates? Under the old PDC system, yes, at the end of a contract. Under the license system, the framework is set by MLB, and changes go through it.
What is a farm system? The set of minor league teams and players under a major league club's control, a term popularly traced to the chain of clubs the Cardinals built in the 1920s.
What does optioned mean? A player on the 40-man roster is assigned to the minors without being waived. He can be recalled to the major league roster.
Do the minor league teams keep their names? Yes, most local names and mascots remain, although the leagues and level names have been reorganized.
Where to go next
If you are tracing how players arrive in the system, read the history of the amateur draft. For the leagues that sit at the top of the system, read the Pacific Coast League and the International League. To follow prospects on this site, see the minors section and the minor league baseball topic page. And for how ties in the standings are resolved at the top level, see how MLB tiebreakers work.