Looking back on his lost 2016, Sandoval acknowledged in a joint interview with ESPN.com's Scott Lauber and ESPN Deportes' Marly Rivera that he started to take things for granted.
"My career had fallen into an abyss because I was so complacent with things that I had already accomplished," Sandoval said. "I did not work hard in order to achieve more and to remain at the level of the player that I am and that I can be."
Sandoval was able to squeeze a career's worth of accomplishments into his first seven seasons with the San Francisco Giants. He was part of three World Series-winning teams in 2010, 2012 and 2014. He also earned a spot in two All-Star Games and was the World Series MVP in 2012.
His success did not translate to the American League when he signed with the Red Sox prior to the 2015 season, however. He hit .245/.292/.366 in 126 games during his first year with the team and lost the starting third base job to Travis Shaw in spring training ahead of the 2016 campaign.
His 2016 season ended before it began, as he had six at-bats over three games before being ruled out for the year with an ailing shoulder that required surgery in May.
"Things definitely happen for a reason," Sandoval said. "[The surgery and rehab process] have helped revitalize that fire in me to win again."
There is photographic evidence to suggest Sandoval is not just talking a big game, with Dan Roche of CBS Boston passing along this image from Alvaro Hernandez:
Sandoval touched on his new routine to get in better shape and keep the weight off:
I have been following a really strict routine that has taken a lot of dedication from my part. It has not been easy to wake up every single day at 6:30 in the morning to then head to the gym and start a full day of work. But you have to have that kind of dedication if you want to achieve the goals you have set for yourself.
Weight has been an issue for Sandoval throughout his career.
During an April appearance on Toucher and Rich (via Samer Kalaf of Deadspin), CSN New England's Sean McAdam reported the Giants made special arrangements at hotels so he couldn't order room service.
Looking ahead to 2017—with the Red Sox among the favorites to win the World Series after securing the American League East title last year and adding Chris Sale to the starting rotation in a trade with the Chicago White Sox—Sandoval knows the task in front of him.
"I am not taking anything for granted," Sandoval said. "I am here to work hard. I'm not thinking about the position or not. I am starting from scratch, and I am here to show what I can do on the field."
In addition to extending his career by getting into better shape, Sandoval said the birth of his child earlier this year has also served as an inspiration:
Watching 'Baby Panda' grow up and that he gets the opportunity to see his father play in the majors for seven, eight more years, to get back to the success I had, that's my motivation every day. The people that I surround myself with now and my family, they are the key to my success. This has been a life lesson.
Sandoval has been one of the most criticized and scrutinized players in Major League Baseball since signing with the Red Sox, which is one of the pitfalls of playing in one of the biggest baseball markets in the country.
Things fell apart for Sandoval in 2016, but the upside of rock-bottom is that it leaves nowhere to go except up. He's taking the physical steps to be in position to contribute for the Red Sox next season.
The one big hurdle left for Sandoval to clear is mental, which won't offer a definitive answer until the games start in April.