Aledmys Diaz does not fit into the categories that we typically use when evaluating baseball signings. Because of Diaz's unique origins, there has been come confusion about when he will become a free agent. The collective bargaining agreement (CBA) which governs labor relations between MLB and the MLBPA has the answer (provided the Cardinals and Diaz didn't sign a contract foregoing arbitration eligibility like other teams have done with other Cuban defectors).
The CBA places a hard cap on the amount of money MLB clubs can spend on signing bonuses for international amateur free agents. The spending limits are enforced by harsh penalties. On top of limiting the overall amount of money club's can dish out, the CBA also proscribes them from entering into major-league contracts with international amateur free agents (just as it does for players drafted in the June amateur draft). If you're a ballplayer, it's best to either not be "international" or "amateur" under the CBA.
What does "international" mean under the CBA?
Attachment 46 of the CBA is entitled "International Amateur Talent." Among other things, this attachment addresses the international amateur free agent bonus pool system. It defines "international" as those players who are not residents of the United States, Puerto Rico, or Canada. If a player hails from any other country or territory on the planet except those three, he's considered international talent under the CBA.
What does "amateur" mean under the CBA?
In order for money paid to an international player to fall under a club's international amateur free agent bonus pool, the player signed must be both "international" and "amateur." The definition of "amateur" is set forth more by negative implication than positive definition. The CBA contains exemptions, one of which is specifically crafted for Cuban defectors.
From 2012 through 2014, Cuban players who (1) are 23 years of age or older and (2) have played as a professional in a Cuban professional league for three seasons or more are exempted from international amateur free agent bonus pool restrictions. After the conclusion of the current 2013-2014 signing period, Cuban players are only exempted if they (1) are at least 23 years old and (2) have played as a pro in a Cuban league for at least five seasons.
Diaz defected from Cuba while in the Netherlands for a tournament in 2012. At that time, he had played in the Cuban National Series for four full seasons and part of a fifth. But he was only 22 years old when he attempted to register with MLB during the 2012-2013 signing period. Diaz lied about his age. He said he was 23, presumably to avoid being considered an amateur under the CBA. MLB caught him and forced him to wait a year—until the 2013-2014 signing period—to test the free-agent waters of MLB. This winter, Diaz met the criteria to be exempted from MLB clubs' international amateur free agent bonus pool and the Cardinals signed him for $8 million (which is more than the total dollar amount of any individual club's amateur international free agent bonus pool in 2013). The St. Louis-Diaz agreement is also a major-league contract; remember, that is something international amateur free agents are prohibited from doing under the CBA.
In Four Years, Free Agency Again or Arbitration?
Under the CBA, a major-leaguer earns the league minimum for his first three seasons. After three seasons of MLB service, a player becomes arbitration eligible. For years four through six of his big-league career, he can file for salary arbitration, a process in which an independent arbitrator determines the player's salary based on myriad of factors. As a general rule, players typically earn about 40% of what they'd get on the free-agent market in year one of arbitration, approximately 60% in the second year, and around 80% in year three.
Article XX(B) of the current CBA sets forth when a ballplayer qualifies for free agency. So long as the player has not previously entered into a contract for the following year (like Matt Carpenter just did), he is eligible for free agency after he has logged six years of MLB service time.
Now, you may be thinking to yourself that other Cuban defectors are not under club control despite the fact that they will not have six or more years of MLB experience before the expiration of their contracts. This is true. As free agents, some of these players negotiated deals with provisions that allow them to forego arbitration. For example, both the A's and Yoenis Cespedes signed away their ability to arbitrate in 2016 and 2017 when they agreed to their current four-year contract.
A Cuban defector who signed a major-league deal yet is still arbitration eligible can be found in the National League Central. Ardolis Chapman's six-year contract with the Reds allowed him to convert into a bonus the $3 million he was due for 2014 under the deal if he was eligible for arbitration. Chapman was arbitration eligible this year, so he converted the money into a bonus and filed. (Opt-out clauses like the one in Chapman's contract were also common for players who signed MLB deals after being selected in the amateur draft. The Nationals and Bryce Harper clashed on including such a clause in his major-league deal, which could make for an intriguing grievance hearing.)
As of this writing, there is no indication that the Cardinals and Diaz agreed to forego arbitration if the infielder proves eligible for such after the expiration of his current deal. Diaz and the Cards entered into a four-year contract, which means that the newest St. Louis prospect will not be able to accrue the requisite amount of service time to qualify for free agency under the CBA at the time his current contract ends. The Cardinals should have Diaz under club control for at least two years after his current contract expires.