"He had some pretty good swings for a guy that doesn't play all the time and typically plays against left-handed pitching, and you've got a right-hander on the mound that's been unbelievable on righties," A's manager Bob Melvin said.
Entering the day, Gonzalez had held right-handed opposition to five hits in 52 at-bats (.096) through his first four big league starts. His third came against the A's in Oakland, where Phegley went 0-for-3 with a walk.
The A's catcher, who was making just his 11th start of the season against a right-hander, grounded out in his first at-bat but drove a solo shot to left-center field in his return to the plate in the fifth. Phegley's two-run double in the sixth marked the end for Gonzalez.
"I kind of knew his game plan against me and it worked pretty well last time," Phegley said. "He just kind of pounded me in with that two-seamer. I was telling the guys, I think before he was starting it on the corner and running it in for balls, jamming guys. Tonight, he was just more on the plate. He just didn't have that action like he had last time. That might be rare for him. I don't know. It seems like he's having a good year.
"He just threw some balls that we could get the barrel on, and luckily we got to him."
Phegley's efforts helped starter Jesse Chavez earn the win, despite the right-hander allowing a season-high five runs in five innings.
"Not only did we get him off the hook, we got him something he deserved," Melvin said, "because there's been so many times he's the guy left out there with no support with a team that can score some runs."
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.