is considered Class AAA, but the league’s 16 teams operate quasi-independently and are not affiliated with major-league franchises the way teams in the US-based minor leagues are.

Truth in the Minor League Class Structure: The Case for the Reclassification of the Minors

This article was written by John Cronin

This article was published in Spring 2013 Baseball Research Journal

The current minor league class structure was established with the 1963 baseball season. Since then, the practice of grouping the minor leagues into four classes has become confusing to say the least. The four classes are a fallacy; there are really eight classes in existence.

is considered Class AAA, but the league’s 16 teams operate quasi-independently and are not affiliated with major-league franchises the way teams in the US-based minor leagues are.The highest minor league class is currently AAA, consisting of the International, Mexican, and Pacific Coast Leagues. Players on the rosters of the teams in these leagues are typically waiting for a call to the major leagues for the first time or a return call to The Show. This classification requires no change at the present time. The International League with 14 teams and the Pacific Coast League with 16 teams serve as the top farm clubs for the 30 major-league teams. The Mexican League’s 16 teams operate in a quasi-independent manner. While a member of Organized Baseball, the Mexican League’s teams are not major-league affiliates. This has been the case for most years since its establishment in 1925 as an independent league. It joined Organized Baseball as a Class AA minor league in 1955 and was elevated to Class AAA for the 1967 season. 

The next level is Class AA, encompassing 30 teams each with a major-league affiliation and divided into three leagues: Eastern (12), Southern (10), and Texas (8). Most players in these leagues have been playing ball professionally for several years, moving up from the lower classes. This classification also requires no change at the present time.

The confusion and the blurring of the minor league classifications occurs at levels below AA. From 1946 to the end of the 1962 season when the current minor league structure was adopted, there were six distinct classes of minor leagues: AAA, AA, A, B, C and D. 

Major league teams developed vast farm systems during the 1930s and 1940s. It was common for teams to have several farm teams at each classification, and dozens of teams dotted the country. Minor leaguers could be promoted, demoted, or moved laterally during their career in the bushes. Then there was the Pacific Coast League, which held a different designation. In 1946 the classification structure was changed to eliminate Class A1 and establish Class AAA and the PCL was reclassified from AAA to a newly created Open Class in 1952. This was done because there was a possibility that the PCL might become the third major league. The league kept the Open Classification through the 1957 season. It returned to Class AAA for the 1958 season. As a result of the relocation of two major league franchises to the West Coast—the Dodgers and Giants—the idea of the PCL becoming a major league was shelved. 

As a result of several factors, notably the rise of television in American homes, the minor leagues went into a period of decline beginning around 1950. The decline continued during the 1950s and into the early 1960s. As a result of the contraction in the number of minor league teams and leagues, Major League Baseball intervened with a plan to rescue the minors. As a part of this plan, with the start of the 1963 season the minors were reclassified and reduced to four classes: AAA, AA, A, and Rookie. 

Class AAA was reduced from three leagues to two when the American Association was disbanded. The four surviving teams of the defunct league were absorbed into the International and Pacific Coast leagues. 

The two 1962 Class A leagues, the Eastern and the South Atlantic (“Sally”), were elevated in 1963 to Class AA where they joined the two existing AA leagues, the Texas and Mexican. The South Atlantic League changed its name in 1964 to its current name, the Southern League.

The restructuring at the next level included the two Class B, the four Class C, and five of the seven Class D leagues (one folded). They were all upgraded to the new Class A. The one remaining Class D league, the Appalachian, was given a new classification, Rookie. 

This structure was in effect until 1966 when the A class needed to be expanded. The previous year, the Northern League had gone from playing a full season to playing from the end of June to Labor Day, and in ’66 the Northwest league adopted the shortened season, also. (In previous years, the only leagues that had played an abbreviated schedule were the ones at the Rookie level.) Class A was thus divided into two subclasses, Class A and Short-Season Class A. The new system must have been too restrictive since it was in effect for only three seasons, whereas the previous structure had been in effect for seventeen seasons with relatively little change.

After the change in 1966, minor league classifications stayed the same until the start of the 1990 season. That year, Class A baseball was further subdivided with the creation of a third subclass, Advanced A. Three leagues, California, Carolina, and the Florida State League, were placed in this Class A subclass.1

The structure introduced for the 1990 season has been in effect through the 2012 season. This structure may cause confusion to the novice and/or casual baseball fan. Even avid fans that are only “major-league conscious” could be easily confused by this classification system. They could hear about a very good prospect that has spent the last three seasons in Class A ball and question why that player has not advanced to Class AA or Class AAA. In reality, the player could be making steady progress in the minor leagues. To illustrate, Joe Baseball, an imaginary minor league player, graduates from college and is selected in the 2010 First Year Draft. He signs a contract with the major league team that drafted him and is assigned to that team’s Class A Short-Season farm club. Joe has a decent rookie season and is promoted and assigned to the club’s Class A affiliate for 2011. Again, he has a good first full season as a professional baseball player and his team rewards him with a promotion to its Advanced A team for the 2012 season.

However, unless the fan understands the current minor league class structure, they will be confused. The minor leagues need a new classification structure to reflect the true reality of the minor league system at the lower levels. Class A is three different classes that need to be clearly delineated. Players in Advanced A, A, and Short-Season A are really at three different stages of their careers, but are not presented as such. As had been previously discussed, a minor league player back in the “old days” could be moved laterally in the team’s voluminous farm system. This is not the case in today’s baseball economics. Each major league team has only one team at each level. (This does not hold true for the Dominican Summer League where several major league teams have two separate farm teams in that league.) Today, every time a minor leaguer changes teams in the farm system, he is getting promoted or demoted. 

I propose a new minor league class structure to eliminate confusion and to more accurately reflect the different levels currently present in the minor leagues. My recommendation is to revive the nomenclature in existence from 1946 to 1962 with two minor modifications. The system would have the following classes: AAA, AA, A, B, C, D and two additions to that old system, Rookie and Pre-Rookie. 

Using the leagues in existence for the 2012 baseball season, the new Minor League Classification Structure would be as follows:

  • AAA: would remain the same as presently classified. The International, Mexican and Pacific Coast Leagues would remain as Class AAA leagues.
  • AA: would also remain as presently classified. The Eastern, Southern and Texas Leagues would remain as Class AA leagues.
  • A: current Advanced A leagues would now be classified as Class A leagues. The California, Carolina and Florida State Leagues would be in this class.
  • B: current A leagues would now be classified as Class B leagues. The Midwest and South Atlantic Leagues would be in this class.
  • C: current Short Season A leagues would now be classified as Class C leagues. The New York-Pennsylvania and Northwest Leagues would be in this class.
  • D: the two current “non-complex based” rookie leagues in the United States would now be classified as Class D leagues. The Appalachian and Pioneer Leagues would be in this class.
  • Rookie: the two current “complex-based” rookie leagues in the United States would now be classified as Rookie leagues. The Arizona and Gulf Coast Leagues would be in this class.
  • Pre-Rookie: current foreign rookie leagues would now be classified as Pre-Rookie leagues. The Dominican Summer and Venezuelan Summer leagues would be in this class.

A distinction between the “complex-based” rookie leagues in the United States and the foreign rookie leagues is necessary. Many players spend one or two seasons in the foreign leagues and then leave those leagues for “complex-based” teams in the Arizona or Gulf Coast League. Since in the current baseball economics, duplications are not practical, it is entirely appropriate to declare that these players are “being promoted” from the foreign rookie league to the United States “complex based” rookie leagues. These four leagues represent two different player classes. 

Some might argue that differences between the subclasses of Class A ball are subtle and not distinct enough to require three separate classes. If that were so, players would be assigned and reassigned to the three subclasses interchangeably. This is not what is in effect. Players are assigned based upon their experience and current skill level. In Table 1, I demonstrate the correlation between players’ ages and subclass of A in which they play, using Batters’ Average Age from for all 2012 minor leagues. To put it simply, the older, more experienced player usually plays ball at a higher level. 


Table 1: Proposed League Classification

League Current
Average Age
Mexican AAA AAA 29.7
International AAA AAA 27.5
Pacific Coast AAA AAA 26.8
Eastern AA AA 24.4
Southern AA AA 24.3
Texas AA AA 24.1
Florida State Advanced A A 22.8
California Advanced A A 22.6
Carolina Advanced A A 22.6
South Atlantic A B 21.7
Midwest A B 21.6
New York-Pennsylvania Short-Season A C 21.1
Northwest Short-Season A C 21.1
Pioneer Rookie D 20.9
Appalachian Rookie D 20.2
Gulf Coast Rookie Rookie 19.7
Arizona Rookie Rookie 19.4
Dominican Summer Foreign Rookie Pre-Rookie 18.6
Venezuelan Summer Foreign Rookie Pre-Rookie 18.3


It is not surprising that the Mexican League had the average age of 29.7 for AAA, two and three years older than the International and Pacific Coast Leagues, respectively. Since the Mexican League does not have major league team affiliations, most players in that league make it their career and stay there. There are few Mexican League alumni playing in the major leagues. The ages of the players in each league give a clue as to skill level in that league. As the Table shows, there are age breaks of one year or more, which suggest that is where the class divisions do indeed exist. 

The only real anomaly in Table 1 is in the proposed Classes C and D. The reason for the lower classification for the Arizona and Gulf Coast League is that the players are in a complex-based set-up that suggests younger, less experienced, and raw rather than refined talent. I believe that these two leagues are a notch below the Pioneer and Appalachian Leagues, which are more traditional minor leagues.

Beyond this workable classification structure within MLB’s affiliated farm systems, this structure could be adopted by the independent minor leagues in the United States and Canada, and the foreign professional leagues around the world. 

Since the early 1990s, there has been a resurgence in independent minor leagues in the United States and Canada. Table 2 shows the six independent leagues that played ball during the 2012 season. One of these leagues, the North American, has since folded.


Table 2: Independent Minor Leagues

League Teams First
Atlantic 8 1998 29.8
North American 10 2011 28.2
American Association 13 2006 27.1
Canadian-American Association 5 2005 26.1
Frontier 14 1993 24.2
Pecos 6 2011 24.1


The problem with these independent leagues is that there is no benchmark for the quality of play in these leagues. What minor league class should each league be in? In order to more fully promote consistency in minor league classification, I believe that these leagues need to be assigned the appropriate classification. The question is how to accomplish this and who is going to do it? Do we allow the leagues to classify themselves? Independent baseball executives definitely have an opinion as to the level of play in their leagues. Miles Wolff, Commissioner of the American Association and the Canadian-American League, stated that he would classify the Atlantic League as AAA, the American Association and the Can-Am as AA, the Frontier as A and the Pecos as the old Class D. He is quick to point out the quality of player within a given league is not necessarily consistent. He relayed an interesting comment made by Hal Lanier, the former major league player and manager who was a longtime independent league manager. Lanier stated that when his number one pitcher in the rotation starts, then the play is Class AAA, but when the fifth starter goes, then it is lower Class A.2

The opinions of league officials could serve as a good starting point in the process. However, an independent evaluation would need to be conducted for accuracy. Each league and its teams could be observed, examined, and reviewed by knowledgeable baseball people such as scouts, minor league managers, and coaches for a reasonable time period. These individuals would then present a report with a recommended classification. Since these leagues are independent—and as with all minor league teams have rosters that are very transient—the leagues would be subject to re-evaluation after a certain number of years, say three to five years, in order to protect the integrity and consistency of the ratings.

This proposal for the independent leagues would be similar to the way that the Mexican League, previously discussed, fits into Organized Baseball. In fact, the independent leagues approached Organized Baseball back in 1993 about membership in the National Association with a set-up similar to the Mexican League. This would bring all professional leagues in North America under one governing body and create a uniform class structure necessary for the proper evaluation of all minor league players. However, Organized Baseball indicated that the independents could apply for membership but that it would not result in gaining membership.3 

Maybe now is the time to revisit this possibility. The independent leagues now serve as an additional talent source, supplementing the affiliated minor leagues. The major leagues honor independent minor league contracts and purchase the players. Major league organizations pay independent teams $3,000 in-season and $1,000 off-season to purchase player contracts. If the independents were to gain membership in the National Association, then it might make it easier for these teams to conduct business, trading and/or selling their players to major league organizations. These independent clubs could also opt in to the Rule 5 Draft that occurs every December. This would result in increased revenues for the independents—how much would depend on the league’s classification. If an independent league team was to be classified as AAA, then the team would receive $50,000 for each drafted player. At Class AA, they would receive $12,000, and at Class A, $4,000. Even the lowest amount is still more than they currently receive. 

However, I would propose that the independent teams not be allowed to draft players because transferring a player from a major league organization to an independent team would be counterproductive for the drafted players. Miles Wolff, the commissioner of two independent leagues, indicated that he would favor such a policy.4

The foreign professional leagues also need to be included in this new classification structure. Table 3 lists five of the foreign professional leagues that were in existence during the 2012 season.


Table 3: Foreign Leagues

League Teams First season
Japan Central 6 1950
Japan Pacific 6 1950
Korean Baseball Org. 8 1982
Australian Baseball 6 1989
Dutch Major 8 1999


The same evaluation process that would be employed for the independent minor leagues would also be used for the foreign leagues. However, these foreign leagues could be given the option to be placed in an Open class. The classification used for the PCL from 1952 to 1957 would fit perfectly for these leagues. These countries view their leagues as major league baseball (the Dutch league even has it in its title) and it might be difficult to accept anything less than that. This I believe would be especially true for the two Japanese leagues that have had a long history dating back over sixty years. These league officials might still balk at the prospect of being classified by the United States major leagues. However, with more players coming from these foreign countries, Major League Baseball (MLB) considers them sources of talent. Baseball Prospectus is already utilizing the Japanese Leagues’ data in its PECOTA projection system for their players coming to play in the United States. Since the data from the Korean Baseball Organization lack reliability, they have not been used yet, but stat analysts at BP hope to incorporate them for talent evaluation purposes in the future.5

Other foreign leagues may soon become talent sources for MLB, as well, including the Chinese Professional Baseball League and the Italian Baseball Leagues. It is my belief that these leagues could become true major leagues. The World Series could then truly be a World Series.

If these proposed changes were enacted, in my opinion, there would be clarity and transparency in the minor league classification system. This would then reflect the reality of the actual situation and there would finally be “Truth in the Minor League Class Structure.” 

JOHN CRONIN has been a SABR member since 1985 and serves on the Minor Leagues Committee as a member of the Farm Club Subcommittee. He is currently researching pre-1930 farm clubs. Cronin is a lifelong Yankees fan with a special interest in Yankees minor league farm teams over the years. He is a C.P.A. and a retired bank executive, who has a B.A. in History from Wagner College and an M.B.A. in Accounting from St. John’s University. Cronin resides in New Providence, NJ. 



1 For a clear concise recap of minor league classification history back to 1902, see

2 Telephone interview with Miles Wolff on February 12 and 14, 2013.

3 Telephone interview with Miles Wolff on February 12 and 14, 2013.

4 Telephone interview with Miles Wolff on February 12 and 14, 2013.

5 Cecilia Tan, personal communication, via email correspondence, February 13, 2013.