Arbitration Question

[Enjoy Terror]

http://www.baseball-reference.com/teams/BAL/2012-roster.shtml

I was checking out the payroll stats for the Orioles, and this chart cleared some things up about the arbitration process. My question is why do some players get a fourth arbitration year while some only have three before free agency?

EDIT: Also, how does Chen's contract work that he goes back to arbitration for two years after his contact ends with us? Is he automatically under Oriole control until 2017? Why only two years?

[Crazysilver03]

http://www.baseball-reference.com/teams/BAL/2012-roster.shtml

I was checking out the payroll stats for the Orioles, and this chart cleared some things up about the arbitration process. My question is why do some players get a fourth arbitration year while some only have three before free agency?

EDIT: Also, how does Chen's contract work that he goes back to arbitration for two years after his contact ends with us? Is he automatically under Oriole control until 2017? Why only two years?

Players get a 4th year of arbitration if they qualify as a Super-Two player.

Without knowing the contract details, Chen will most likely be a free agent when his contract is over. Same as Wada at the end of next year.