Rangers general manager Jon Daniels said Monday that Greene's agent, Mike Milchin, reached out to him Sunday and told him that the infielder was "having a recurrence of issues he's dealt with in the past."
Greene dealt with social anxiety issues last season, spending two separate stints on the disabled list and missing 46 games with the St. Louis Cardinals.
"I can't tell you at this point whether he's going to look to come back or when," said Daniels, who added that the club would be supportive of Greene during the process. "We are going to be open-minded and leave that door open, at the same time, we're going to go forward and plan as if he's not going to be here. We'll look to put the club together without Khalil in the picture and if that changes at some point, we'll adjust."
Greene, 30, was signed by the Rangers in January for a one-year, $750,000 contract. He was expected to play all four infield positions, if needed. Shortly after signing, he addressed his anxiety issues in a conference call with reporters.
"I feel like at that point, it was something that was lingering as far as having unresolved personal things," Greene said then. "I won't get into specifics, but I don't think it's any different than a lot of people as far as stresses and pressure of everyday life on the field and off the field. I was carrying that on the field where the game itself becomes an obstacle. It wasn't the primary obstacle, but it was difficult."
But he said he was excited to return and was enjoying playing baseball again and preparing for the season.
Arias, who is out of options, arrived in camp on Monday and said he was focused on earning a spot with the club. He said he had not heard any news on Greene.
"I don't want to play in [Triple-A] Oklahoma again," Arias said. "I want to play in the big leagues. It's my time."
Arias batted second and played shortstop in winter ball in the offseason and said he arrives in Arizona feeling 100 percent in terms of how his body is performing. Arias said he's put 2007 behind him, when arm trouble began to slow his progress toward the majors.
The Rangers, along with Greene's agent, have to figure out where they go from here. Greene could go on the restricted list, which requires an application through Major League Baseball.
If he goes on that list, he would not get paid, but the contract would stay in place whenever he comes off it. He would also not count on the 40-man roster. The Rangers could also look at voiding the contract.
"This is an amicable situation," Daniels said. "We're going to work with Mike Milchin and Khalil. The priority here is to get him some time and some privacy to deal with the matter."