"I think this is kind of how the situation works for somebody in my situation," said Niemann, calling his decision a procedural one and noting that it's likely he would have been non-tendered by the team anyway since he is recovering from shoulder surgery.
When asked if he would like to return to the Rays, Niemann said, "Absolutely. I was born and raised by those guys. ... It's been an honor to be a part of what has happened to the organization since I've been here."
The Rays drafted the 6-foot-9 right-hander out of Rice University in the first round (fourth overall) of the 2004 First-Year Player Draft. He first reached the Major Leagues in 2008, when he made five appearances.
Niemann went on to become a mainstay in Tampa Bay's rotation before fighting injuries that limited him to eight starts the past two seasons.
After beginning the 2013 season in the bullpen, Niemann did not pitch before having to undergo surgery on April 10 to repair the labrum and rotator cuff in his right shoulder, a procedure that carried an estimated 9-12-month recovery.
When pressed for when he might return, Niemann said he was optimistic about making a few rehab starts in April and May before "rolling into the season." But he added that a second-half return would be more likely.
"Things are going well, but I do not have any deadlines," said Niemann, who added that he did not have a deadline about when he might sign a contract, either, noting that teams will likely want to see him throw before signing him.
Niemann's best season was his rookie campaign in 2009, when he went 13-6 with a 3.94 ERA in 31 appearances. He is 40-26 with a 4.08 ERA in 97 career appearances, all for the Rays.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.