Saunders has appeared in just nine games this season because of ongoing issues with his knee. He tore the meniscus during Spring Training and then underwent a surgical procedure to have 60 percent of it removed from his knee.
The 28-year-old returned in late April but wasn't himself on the field. He was later diagnosed with a bone bruise, and he'll likely need another couple of weeks before he can start load-bearing exercises, which would then eventually lead into a rehab assignment.
"This isn't necessarily common, but it has happened before, and the annoying thing with the bruise is you've just got to rest it, otherwise it will come back and it will never go away," said Saunders, who was acquired during the offseason in a trade with the Mariners for left-hander J.A. Happ.
"I've been going on six weeks now, and it'll be a couple more weeks, but it's definitely showing good signs of improvement comparing MRIs [Monday] and six weeks ago. It's a drastic difference in the improvement of my knee. Basically once it's gone, I shouldn't miss too much other than my timing."
Chris Colabello has taken over the starting duties in left field while Saunders has been on the disabled list. Ezequiel Carrera also has seen some time in left while serving in the role of fifth outfielder.
Saunders is a career .230 hitter with a .301 on-base percentage and .682 OPS in 562 games. Last year with the Mariners, Saunders hit .273 with eight home runs and 34 RBIs in 78 games.
"The hardest thing was just rest and just sitting down and forcing myself not to do anything to allow the bone bruise to heal," Saunders said. "It's definitely getting better ... I'm starting to see light at the end of the tunnel."
Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, follow him on Twitter @gregorMLB and Facebook, and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.