Franco sent the first-pitch, 97-mph fastball from Hansel Robles a projected 431 feet, making it the Phillies' longest home run of the season, according to Statcast™. The ball left his bat at 106.7 mph.
"I know him," Franco said. "He's from the Dominican, and he's got a good fastball. I just went out there and didn't worry about my first two at-bats. I just tried to make good contact and a good swing, and it happened."
• Grand slams mean 40% off pizza
Franco also hit a broken-bat single to center field to lead off the ninth.
"The base hit in the ninth inning goes to show you he wasn't trying to tie the game up with one swing of the bat," Phillies manager Pete Mackanin said. "He was trying to get on base. He got a base hit. That's the kind of thing that is important to me. Little by little, he's going to get there. That was a huge home run. It was also a huge base hit."
The Mets swept the series, but Franco went 5-for-11 with two home runs, six RBIs and one walk. He did not strike out. Franco had hit .136 (3-for-22) with one double, two RBIs, three walks and five strikeouts in the season's first six games.
"Right now, everything is slowing down for me," Franco said.
Todd Zolecki has covered the Phillies since 2003, and for MLB.com since 2009. Follow him on Twitter and Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.