Vincent's news, however, was not expected, although the 29-year-old gave up back-to-back home runs in his last outing, Sunday's 11-6 loss to the Cardinals.
Vincent is 2-3 with a save and a 3.47 ERA in 35 appearances, with 42 strikeouts and nine walks in 36 1/3 innings.
After being acquired by trade from the Padres just prior to the start of the season, Vincent has been one of the most reliable members of the Mariners' bullpen. He leads the relievers in appearances and strikeouts and is second in innings pitched.
"He's been really big, for a guy we didn't even have in a Mariners uniform until late in March," manager Scott Servais said. "He's done a great job. We used the tar out of him. We really overused him, and that's just what happens when the starting rotation isn't getting as deep. All of the sudden those sixth- and seventh-inning guys get overworked, and that's what happened."
Vincent said he's made more multi-inning appearances this year than he's used to and his back started troubling him after throwing back-to-back games at the Rays June 14-15, going 2 2/3 innings the second day in a game the Mariners lost in 13 innings.
"After that, it locked up and just hasn't unleashed from that," Vincent said. "I tried pitching through it and obviously it's not working. We'll give it 15 days and go from there and be ready after the All-Star break probably."
Vincent said he'll rest completely for the next five days to let the back quiet down, then begin working his way back.
"I can throw, but I'm not throwing the same so I can't get on top of the ball," he said. "I'm not helping the team at all right now. I need to get healthy. This team is really good and it makes me sick going out there and I've lost three or four games. It makes me sick when I know this team is this good and we've got a chance to do something."
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.