But manager Scott Servais wants to see some progress from Walker before he takes the next step. The club hopes extended rest has helped alleviate the pain that had been nagging his push-off foot since mid-June.
"He threw a bullpen in Toronto [last weekend], but it wasn't that great," Servais said. "He felt fine, but the ball wasn't really coming out that well. So he needs to get after it tomorrow in the sim game. I don't want him just flipping balls in there. He needs to get after it and treat it like a real game."
Walker, 4-7 with a 3.66 ERA in 16 starts, figures the adrenaline will flow in a game-type situation.
"If someone is in the box and swinging, it's competitive," he said. "Another thing is having a radar gun on will help. If my velo is 89-92 [mph], then I'm not normal. If I'm back to 94-96, then everything is going good."
The tough thing with Walker's injury has been that he doesn't usually feel any problem in the foot until he gets into a real game situation and begins pushing off the rubber with full force, so the Mariners want to test that out before beginning his Minor League rehab stint.
"I think he's going to be fine," Servais said. "That's the way I'm looking at it."
• Reliever Nick Vincent didn't make the road trip with the Mariners, but his back strain is beginning to feel better, according to Servais. Vincent, on the 15-day DL since June 27, played catch at 120 feet on Tuesday and figures to advance to a bullpen session shortly. Servais said he'll need a live batting-practice outing and several Minor League rehab outings before being ready since he's been sidelined nearly a month.
• There was some thought the Mariners might add a position player for the Interleague games against the Pirates and Cubs, but no move was forthcoming on Tuesday. It didn't help that outfielder Guillermo Heredia, a potential candidate for promotion, hurt his shoulder on Saturday and wasn't able to play in Triple-A Tacoma's last two games.
"I think we're going to stay with what we've got," Servais said. "Obviously it's a crazy week with all the stuff going on throughout baseball [heading into Monday's non-waiver Trade Deadline]. We're just going to hold still right now."
• Lefty reliever Charlie Furbush is scheduled to pitch in back-to-back games later this week for Tacoma, which would be another necessary step in his return from a year-long absence due to shoulder problems.
• Shortstop Ketel Marte, on the 15-day DL with mononucleosis, was feeling better and reported to Safeco Field to do some light work and play catch on Tuesday. Marte has been sidelined for a week, but Servais said there's still no timetable on when he might be back and that he'll need to regain seven or eight pounds and get his strength back before any return is possible.