Cishek was pulled off his first Minor League rehab assignment and has spent time with Mariners pitching coach Mel Stottlemyre Jr., throwing several bullpen sessions and then a 25-pitch simulated outing when Seattle was home last week.
"He did make some strides in a couple bullpen sessions," Servais said. "The slider had the late break, the ball had more life coming out of his hand. He felt better about it and responded better physically the next day than he had in the past. So I think he's getting more comfortable using his legs.
"That's a big part of his delivery. Even though he's a side-arm guy, he's got a lot of moving parts, which helps create his deception. But you've still got to use your legs when you're on the mound throwing, and he feels better with where he's at. I hope the results are good in Tacoma because we certainly need him."
• Left fielder Guillermo Heredia and starting pitcher Ariel Miranda were late arrivals in Toronto after visa issues kept them off the team plane that flew to Canada from Philadelphia on Wednesday night.
Heredia was replaced in Thursday's lineup by Taylor Motter, while Miranda isn't slated to start until Sunday. Heredia is expected to be available off the bench for the opener and be back in the lineup on Friday.
• James Paxton, sidelined with a strained left forearm, played catch at Safeco Field on Thursday for six minutes at 60 feet for the first time since going on the disabled list on May 5. The session went well and now the left-hander will see how his arm feels Friday before determining the next step in his rehab.
• Felix Hernandez's rehab is on a similar recovery and he is expected to throw for a second time Friday as he works back from bursitis in his shoulder. Hernandez has been out since April 25, so he could need a little more build up time before rejoining the club.
• Hisashi Iwakuma, the Mariners latest starter to hit the DL, flew back to Seattle while the team headed to Toronto and was undergoing tests on Thursday on his sore right shoulder.
• Outfielder Mitch Haniger was scheduled to meet with the doctor on Thursday to hopefully be cleared to resume baseball activities as he recovers from his strained right oblique. Haniger has been sidelined since April 25 and isn't expected back for several more weeks.
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB. This story was not subject to the approval of Major League Baseball or its clubs.