It offered Grandal another reason to think his early-season slump could be over.
"I've been trying to be more aggressively lately," he said.
In the last two days, Grandal has raised his season batting average from .179 to .230.
On Saturday, he collected three hits in a win over the Diamondbacks. On Sunday, he drew a pinch-hit walk, then ended the game with his first career walk-off home run.
The catcher said a minor shoulder problem compromised his swing in the first few weeks of the season, but that his mind wasn't right either.
"Earlier in the season, I got a lot of guys on base, a lot of guys on second and I thought I had to drive them in," said Grandal, who is batting .143 with runners in scoring position.
He said his approach has now changed.
"You have to look behind and who's hitting behind you," he said. "If you just get on first and you let the guy do his job, we're going to be good."
He said that's what he was thinking Sunday when he stepped into the batter’s box to face
But Grandal said he also recalled the home run Joc Pederson hit against Marshall the previous night.
"[Pederson] hit a fastball," Grandal said. "I know [Marshall] has a pretty good fastball. That's what he feels comfortable throwing. I went up there looking fastball and he was able to give me one."
Grandal then deposited the baseball into the left-field pavilion.