A story posted on the VWL's official website said that Sandoval would be available beginning Wednesday to play for Magallanes, which has entered the third round of the league's round-robin postseason format.
Sandoval did not require the Giants' consent to join Magallanes, for whom he has regularly participated in previous years. He was named Most Valuable Player of last year's VWL postseason, batting .333 with four homers.
"As a native player, you don't have to ask permission," Giants vice president and assistant general manager Bobby Evans said Wednesday. "That said, I wasn't aware of it. I'm happy to hear it. That'll be good for him."
The same could be said of Sandoval's weight loss, if the Twitter buzz dealing with the subject is true. His conditioning progress has been chronicled by his brother, Michael, on social media. Sandoval, 27, will be eligible for free agency after this season, when his three-year, $17.15 million contract expires.
Last season, Sandoval hit .278 with 14 home runs and 79 RBIs in 141 games. He hasn't exceeded 20 homers or a .300 batting average since 2011. But the potential to secure a lucrative deal likely has motivated Sandoval, 27, to enter '14 physically prepared. Giants general manager Brian Sabean said during last month's Winter Meetings that he would consider offering a contract extension to Sandoval if the 2012 World Series MVP reports to camp in shape.
"Perhaps his pending free agency is the best medicine," Sabean said.
Since he broke into the Major Leagues with the Giants in mid-August 2008, Sandoval has hit .298 with 90 home runs and 389 RBIs.
Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, and follow him on Twitter at @sfgiantsbeat. This story was not subject to the approval of Major League Baseball or its clubs.