Fellow right-hander Hisashi Iwakuma is also scheduled to rejoin the rotation next weekend -- either Saturday or Sunday against the Astros -- assuming all goes well in his second rehab outing at Tacoma on Monday.
Servais said it's not certain yet who will come out of the rotation at that point. Christian Bergman (3-4, 5.75 ERA going into Sunday's game against the Rangers) and rookie Sam Gaviglio (3-1, 3.41 ERA) have both filled in over the past six weeks and have Minor League options. Veteran Yovani Gallardo has struggled with a 3-7 record and a 6.30 ERA, but doesn't have options.
"We'll have to make some decisions on how we juggle the rotation and move guys around," Servais said. "That decision hasn't been made yet. We'll wait and see what happens here the next few days."
The second-year manager didn't rule out the possibility of going with a six-man rotation initially.
"The idea has come out there," he said. "I don't know how realistic that is. Keeping guys on their normal turn is important, routine-wise. But because we've had some guys coming off injuries, it is something we could kick around. Between Felix and hopefully getting Kuma back, we'll see where we're at there.
"It sounds great in theory if guys are going deep. If guys are going five innings and you've got 4-5 of those guys, that doesn't help you any."
Servais said the reports on Hernandez's final rehab outing were positive.
"The numbers were good," Servais said. "He used all his pitches. The report I got, the first couple innings his fastball was up a little [in the zone]. After that, it was down. Good curveball, good changeup, got his pitches in. The results were really good."
• Shortstop Jean Segura, who has been on the 10-day DL since June 2 with a right high ankle sprain, is expected to begin a brief rehab stint with Tacoma either Monday or Tuesday. Segura likely will play two games with the Rainiers, one at designated hitter and the second at shortstop, before being cleared to rejoin the Mariners.
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.