In his first season with the Red Sox, Pablo Sandoval hit an underwhelming .245/.292/.366 in 505 plate appearances. He showed up to camp noticeably overweight, and in Boston's first eight games this year, Sandoval only accrued 7 PA's. Simply put, he wasn't a part of John Farrell or Dave Dombrowski's plans anymore (despite the former's vote of confidence), and with Travis Shaw hitting .292/.393/.417 and playing significantly better defense than Sandoval, he was essentially wasting a roster spot.
As a result, the Red Sox placed him on the 15-day DL with left-shoulder soreness, which came as a surprise to nearly everyone.
"The curiosity of the DL move grew as the day went on. Sandoval complained of mysterious left shoulder pain, and the Red Sox chose to immediately place him on the disabled list without having tried to diagnose the severity of the injury with an MRI, sources told Yahoo Sports. By the end of Wednesday, Sandoval still hadn't visited an MRI machine, a standard procedure that precedes a DL trip in nearly every case but catastrophic injuries."
While the move was strange, and met with a heavy amount of skepticism, this could be the best course of action for both Sandoval, and the Red Sox. Instead of wasting his time on the bench, Sandoval can take this time to try and work himself into better shape, and Boston can use his vacated roster spot for someone that they can use on a more regular basis. However even if Sandoval can lose some weight, his relationship with the Red Sox might already be too fractured.
"The broken, disastrous marriage between Pablo Sandoval and the Boston Red Sox, an ill-fated union exceeded in its dysfunction only by a Kardashian coupling, could be nearing its end. Here's how ugly it has gotten, major league sources told Yahoo Sports: Sandoval wants to stay in Boston only if he can play every day, and the Red Sox have no intention of playing him unless he loses weight and other in their current lineup struggle."
Even if Sandoval can prove himself to be an above average third baseman once again, the Red Sox may have already decided that they simply don't care anymore. Considering that he's still owed roughly $75 million, and his weight issues haven't been a one time occurrence, Boston would likely want to jump on any value he might rebuild, and send him away to any team willing to take him.
The Padres were reportedly scouting Sandoval during spring training, but according to Passan, they've "cooled on" him since. Without an obvious suitor for the third-baseman, the next course of action for Sandoval is unclear. The Red Sox can't show other teams that he's back to being a productive baseball player without him being in the lineup, and unless Shaw's offensive and defensive production craters, there isn't a way to get Sandoval a significant amount of playing time.
There's no easy solution to this problem, but given that Dombrowksi has fully embraced the concept of Sandoval being a "sunk cost" his days in Boston are likely numbered.