It was a big-time cut on an 0-2 changeup from Francisco Rodriguez that was up and away and probably even out of the strike zone. Sandoval's opposite-field rope to left-center had an exit velocity of 104.9-mph and a projected distance of 414 feet.
The home run was further proof that Sandoval's productive offseason can lead to a resurgent season.
"Yeah, on an 0-2 pitch up and away, he puts an incredible swing on a ball and this is a big ballpark and for him to hit it as far as he did," Red Sox manager John Farrell said.
It was the second-longest home run Sandoval has hit in the Statcast™ Era, and his first regular-season long ball since Aug. 15, 2015.
"With men in scoring position, just don't try to do too much," Sandoval said. "So I just calmed myself a little bit and tried to hit the pitch."
He didn't just hit it -- he squashed it.
It was only the second 0-2 pitch K-Rod has allowed for a home run in his career, and first since 2003.
"I got ahead of him 0-2, and then just threw an extremely bad pitch over the plate, and you guys know what was the result," Rodriguez said. "Should've made a better pitch than that. I was trying to go up and away, waste a pitch, and then maybe go down the barrel, middle-in, to try to get him to chase. It was a setup pitch that got too much of the plate, and he didn't miss it."
Sandoval -- who missed nearly all of 2016 with a labral tear in his left shoulder -- hopes that his next late-innings clutch hit comes in a victory.
"I feel good," Sandoval said. "But it was a tough loss. Tough game. That's more important."
Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.