From BR Bullpen
A free agent is a player who has played at least six years in the major leagues and has played out his contract, has been released from his contract by his parent club, or has been sent to the minors six times.
A free agent is eligible to sign with any club he wishes.
 Further Reading
- Roger I. Abrams: "Arbitrator Seitz Sets the Players Free", in The Baseball Research Journal, SABR, Volume 38, Number 2 (Fall 2009), pp. 79-85.
- Ronald W. Cox and Daniel Skidmore-Hess: Free Agency and Competitive Balance in Baseball, McFarland, Jefferson, NC, 2006.