SEATTLE -- The Seattle Mariners are hoping that a couple of weeks off for right-hander Jeff Weaver will help turn around his struggling season.

The ballclub placed Weaver, who is 0-6 with a 14.32 ERA in his six starts, on the 15-day disabled list with right shoulder tendinitis before Friday's game against the Yankees. With his tough start and his career history, Weaver had been in danger of losing his spot the rotation, even the roster. Left-hander Ryan Rowland-Smith was recalled from Triple-A Tacoma to fill Weaver's roster spot.

"Something hasn't been right the whole time," Mariners manager Mike Hargrove said.

According to Hargrove, Weaver mentioned that his right shoulder did not feel as strong as it should, but the right-hander didn't believe that it was affecting his velocity or effectiveness.

"We finally pressed him on it," Hargrove said. "We continued to talk to him about it, and it did not seem to be getting better. We find out it was a case of tendinitis."

Once the inflammation is under control, Weaver will go through shoulder strengthening exercises. His return date is uncertain.

"I have to do some things physically to get to where I need to be," Weaver said. "The zip and pop on my pitches, my movement and the deception just isn't there. You feel like you have a good game plan, and you're out there making good pitches and getting no results. It could be something else besides mental or anything like that.

"I'm putting the effort into every pitch to get minimal results," he added. "When I tell myself I'm going to hump it up here against somebody and I look up and it's [fastball] 88 mph, that's not where I should be sitting at."

Scott Boras, Weaver's high-profile agent, flew up from Los Angeles for Friday's game to commiserate with his client.

"He's great mentally," Boras said. "There are just certain mechanical things that need to be worked out. It's a situation that he has overcome before."

Weaver was in a similar spot last season when he went through a string of tough outings with the Angels, who designated Weaver for assignment in mid-July and eventually traded him to the Cardinals for a Minor League outfielder. Weaver went on to help the Cardinals win the World Series.

Weaver's strong finish convinced the Mariners to sign him to a one-year, $8.3 million contract during the offseason.

"He has the resiliency to understand that you can be at the bottom of your game and, during the same season, be at the top of your game," Boras said.

Interestingly, it happened a year ago.

"It's something we're getting a handle on," Boras said. "We have a very willing participant and a very team-oriented guy."

Weaver said that he doesn't have any timetable for a return. He's going to talk with trainer Rick Griffin and pitching coach Rafael Chaves about what he needs to do.

"We're going to work from the ground up and take a little time to find a routine to get me where I need to be," Weaver added.

One option for the Mariners could be to send Weaver out to pitch for one of the organization's Minor League teams on a sharpening assignment.