Los Angeles Angels shortstop Andrelton Simmons has decided to opt out of the remainder of the season, with only five games left in the regular season and his team all but eliminated from postseason contention.

Simmons informed the Angels of his decision Tuesday, the team said in a statement. Neither side has specified a reason for his decision.

In a statement released through his agency, ISE, Simmons said, "Major League Baseball and the Major League Baseball Players Association developed an environment and system that empowered players and provided us the opportunity to decide on whether to play or opt out of the season. At this moment, I feel this is the best decision for me and for my family. We don't know what the future holds, but we would like to sincerely thank the Angels organization and Angels fans for welcoming and making us feel at home."

Simmons, a pending free agent, is a four-time Gold Glove Award winner and a career .269/.317/.379 hitter through nine seasons in the major leagues. The 31-year-old accounted for the first major move by Billy Eppler as Angels general manager, when Eppler acquired Simmons from the Atlanta Braves in a high-profile trade involving top pitching prospect Sean Newcomb in November 2015.

Manager Joe Maddon acknowledged Tuesday afternoon that he was caught by surprise when Eppler told him about Simmons' decision. Maddon said he texted Simmons but hadn't yet heard back.

"I've really enjoyed this guy a lot," Maddon said. "I'm a big fan. This guy is a good baseball player, and I've enjoyed the conversations, too. It's just unfortunate. He's really a big part of what we're doing right now."

Simmons missed some time because of an ankle sprain earlier this season and batted .297/.346/.356 with zero home runs in 127 plate appearances. He recently expressed a desire to re-sign with the Angels in the offseason but was noncommittal about the chances of that happening, saying: "I can't pay myself to play here, so it's not my decision."

"This year has presented unique challenges for many reasons, and the Angels respect Andrelton's decision," the team said in Tuesday's statement.

The Associated Press contributed to this report.