The Rays have 10 days to either trade Matsui, release him or place him on waivers.
Rays manager Joe Maddon said the team did everything it could to leave Matsui with options. According to Maddon, Matsui said he'd take some time to mull over his options, including a potential return to Triple-A Durham.
"We don't know how this is all going to work out yet," Maddon said. "It's not a closed book yet, I don't think, here. We wanted to give a lot of the power to him in regards to what he wanted to do."
Shortly after the Rays acquired Roberts from the Diamondbacks, Maddon called Matsui into his office to discuss the decision.
Matsui had already left the stadium by the time Maddon met with the media on Wednesday.
"He was very grateful for the opportunity, and he was also upset at himself for not having performed better right now," Maddon said. "Very accountable, straight up, straightforward guy."
"I think he liked it here. I think he would've liked to have stayed here longer."
"It was nice having him in the clubhouse," pitcher James Shields said. "It was nice to have him on our team rather than hitting home runs against me. He's a great teammate and a good guy, so hopefully the best for him."
Matsui was mired in an 0-for-16 slump -- his last hit came July 1 -- and was hitting just .147 with two home runs and seven RBIs for the Rays since signing a Minor League deal on April 30 and having his contract purchased from Durham on May 29.
Even as the veteran was struggling, Maddon still saw Matsui's quick bat and admired the work he put in during batting practice, when he nearly hit the back wall of Tropicana Field.
"I still see the body is in good shape," Maddon said. "He's just having a hard time getting it going based on no Spring Training [and a] long layoff."
The once-feared slugger, a career .282 hitter with 175 home runs and 760 RBIs across 10 Major League seasons, has the most home runs, RBIs and walks of any Japanese player in MLB history.
"This is a Hall of Fame caliber player, based on the body of work that he's done," Maddon said. "Had he done all of that in the United States, which he may have done had he started here sooner, you're definitely talking about a player of that kind of stature."
"He's always had this way of handling himself that I always found desirable. I thought he was a big game player, a big moment player. As an opponent, you never wanted to have him come up in run-scoring situations."
After a hot start to 2012, in which Matsui hit two home runs in his first three games, the 38-year-old outfielder/designated hitter began to slow, leading to the Rays' decision to remove him from the Major League roster.
Still, Maddon left the door open for Matsui to make a return -- not just to the Majors, but to the Rays.
"You never know when that moment is going to occur that he's actually going to get it back," Maddon said. "I have a ton of respect for this man. Not a little, a ton. So for me, he's a member of the Rays and he's got every opportunity to prove that he's getting it back."
"I can't sit here and tell you that he's done. I'm not going to tell you that, because I've argued with other people in the know before about what they think and what I think, and I still see a life in him and I don't think that he's done, and I've told him that also."
Greg Luca is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.