My understanding is that Prior is subject to arbitration after 2006 since the arbitration rules are part of the collective bargaining agreement that cannot be waived by the individual contracts. In any event, the Cubs will not negotiate mid=season as that is their policy. players can be under contact during their arbitration years. Very few players actually ever reach arbitration. Players have 3 (sometimes 4, if they are super 2s) years of arbitration eligibility but that doesnt mean that they will actually be going to arbitration. It is the standard for teams to sign players to 1 yr contracts before going to arbitration , such as Z, and then giving them another 1 year contract the next year, or signing players to multiple year contacts, sometimes throughout their arbi eligible years and sometimes a year or two after they are eligible to become FAs. So when does Prior become a FA, assuming the Cubs take advantage of all his arbitration years? No player becomes a FA before he reaches 6 years of ML service. Which would mean Prior becomes a FA after 2008. Most likely the next contract will be a 2 year extension, allowing the cubs will "buy out" the remaining arbitration years as Mark will want to at least have the option to test the market ASAP. Outside chance of a 3 year contract delaying his ability to test the market one year, but I feel regardless of his desire to stay with the cubs, prior will not handcuff himself and allow himself to have the negotiation leverage of the option to test the market.