Manager Don Wakamatsu said Friday that Bedard will resume throwing next week and could return during a series at the New York Yankees June 30-July 2.
"Probably the earliest would be in New York," Wakamatsu said. "They injected the dye for the MRI, so he can't throw for three days."
That would leave Seattle about 30 days -- five or even six starts, if all goes well -- to showcase its most attractive trade option before the league's July 31 deadline for trading without waivers.
Bedard can become a free agent after this season, and Mariners first-year general manager Jack Zduriencik has said repeatedly he is seeking moves to restock a depleted minor-league system.
That farm was burned by the five-for-one deal orchestrated by since-fired GM Bill Bavasi in February 2008 that brought Bedard from Baltimore. It sent away a budding star in outfielder Adam Jones, a closer who became an All-Star in George Sherrill and a top pitching prospect in Chris Tillman.
Bedard, 5-2 with a 2.47 ERA in 11 starts, has not pitched since June 7. The 30-year-old missed a start in Colorado last weekend with shoulder inflammation. He went on the 15-day disabled list Wednesday retroactive to June 8.
The 30-year-old didn't pitch last year after July 4. He had surgery on the shoulder in September to remove a cyst.
"We don't think what he's feeling now will end up being related," Wakamatsu said.
On Thursday, Bedard saw the man who performed that surgery, Los Angeles Angels orthopedist Dr. Lewis Yocum. Wakamatsu said Yocum deduced the pain may be from bursitis in the joint but that there is no structural damage.
"You never know with these things, but that was the only thing they could come up with," Wakamatsu said when asked why Bedard has had pain in the shoulder.
Wakamatsu said the man replacing Bedard in the rotation, recently demoted closer Brandon Morrow, will remain with Seattle to work up his pitch count rather than build arm strength while the stakes are lower at Triple-A Tacoma.
"Sending him down? I don't know a better learning environment than right here," Wakamatsu said. "Learn in the environment he's going to pitch in."
Morrow threw 74 pitches and lasted just four innings Thursday in an extra-inning loss at San Diego.
The plan is for Morrow to throw 85 pitches next week at home in a rematch against the Padres. The Mariners want more mileage from those pitches, to save their bullpen.
"Four [innings] is not going to cut it," Wakamatsu said.
The Mariners want Morrow to rely more on his changeup and breaking pitches than on his electric -- and sometimes wild -- fastball.
Johnson was one of three players to leave the team this week because of illness or death of a family member. Johnson missed five games after his mother-in-law died.
Team home runs leader Russell Branyan was in the lineup for Friday night's game against Arizona after attending his grandfather's funeral in Georgia on Thursday.
Mariners' RBIs leader Jose Lopez remained away in Venezuela. His sister there is seriously ill.
The 28-year-old Wilson was with Arizona for 11 games earlier this season. San Diego claimed him off waivers last month and he played 16 games for the Padres.
Wakamatsu said Wilson will join the Mariners on Saturday and will stay at least until Lopez returns. That's not expected until at least Tuesday.