After allowing a first-inning run in the Red Sox's 8-5 loss to the Tampa Bay Rays on Wednesday night, Porcello smashed monitors just below the dugout steps.
"I kind of wish I did that without cameras being on me,'' Porcello told reporters. "I apologize to everyone that had to see that. It's not a behavior that I feel like is representative to me and my personality. The frustration got the best of me.''
Porcello allowed six runs and three home runs in 5 2/3 innings against the Rays. He walked one and struck out seven in the loss.
Porcello has allowed at least six runs in four of his last six starts. The former AL Cy Young Award winner finished July with a 7.94 ERA in five starts, although he went 4-1 in that span.
"I care about this team. I care about the game, and I care about what I'm doing a lot. When that's not happening, it's tough to swallow," Porcello said. "You put a lot of work into it and you go out there every five days and give it up and put our team in a tough spot, it's frustrating."
Boston is 59-50 this season. The Red Sox are 2 1/2 games behind the Rays for the American League's second Wild Card spot.