A former personal trainer for Pablo Sandoval says the Boston Red Sox third baseman needs "a babysitter" to watch over him and keep him from overeating, a temptation for Sandoval that the trainer likened to alcoholism.

"He needs to be smart enough to say there's a problem," said Ethan Banning, owner of Triple Threat Performance in Phoenix, in an interview with the Boston Herald. "It's like the alcoholic that won't admit he's an alcoholic: well, you can't address that you're an alcoholic if you don't ever admit there's a problem."

Sandoval, 29, showed up to spring training overweight, and subsequently lost his starting third-base job to Travis Shaw. He had played sparingly this season before being placed on the 15-day disabled list Wednesday with a shoulder issue.

Sandoval underwent an MRI on Thursday that revealed "a great deal going on in his left shoulder," Red Sox president of baseball operations Dave Dombrowski said Friday, and he will seek a second opinion from Dr. James Andrews on Monday.

Ethan Banning, whose working relationship with Pablo Sandoval ended in early 2012, said Sandoval's brother, Michael, called the trainer this past offseason in hopes the two could reconnect. Ethan Banning/Triple Threat Performance

Banning, who worked to get Sandoval in shape before his All-Star seasons in 2011 and 2012, said that Sandoval has "proven to me and shown consistently that he's got to have somebody like me holding his hand."

"And it's not an exercise thing, it's an eating thing," he said. "Obviously exercise is an important factor in it, a very important factor, but eating is going to be the component that needs to be managed and monitored. We had a chef on staff that cooked all his meals."

Banning told the Herald that when Sandoval went home to Venezuela for Christmas in 2011, he gained 21 pounds in 21 days. When Sandoval returned to the Phoenix area, Banning worked hard to keep the Giants -- who were negotiating a new contract for their All-Star -- from seeing him as the pair worked to shed pounds.

"I would go pick him up at a random location, drive him to the facility so that his car wouldn't be there, so if they dropped in, they wouldn't know he was there," Banning told the Herald. "So for about a three-week period, he had the flu; we had every excuse in the world. We were just trying to rip weight off him again. And it ballooned way out of control."

The hard work apparently paid off, as Sandoval signed a new three-year, $17 million deal in January 2012. He went on to have a second straight All-Star season and was named World Series MVP as the Giants won the second of three championships during Sandoval's tenure with the club.

Following the third title in 2014 and the expiration of that three-year contract, Sandoval hit it big with a five-year, $95 million deal with Boston. But he disappointed in his first season with the Red Sox in 2015, hitting just .245 with 10 home runs and 47 RBIs.

Banning, whose working relationship with Sandoval ended in early 2012, said Sandoval's brother, Michael, called the trainer this past offseason in hopes the two could reconnect.

"I think that he's embarrassed right now," Banning told the Herald. "I think there's going to come this moment that he's going to show everybody that this is not who he is. ... I don't know that it's going to be with me, but he's going to hire somebody like that. I think he's likely going to figure it out. But it's not going to be this season, and likely not with the Red Sox, the way it looks."