If you're looking for clues, however, the club has tentatively lined up Erasmo Ramirez and James Paxton to pitch the following two days after Hernandez makes his final Cactus League start on March 25. Things could well change between now and then, but that at least is the plan as of Tuesday.
After that, there's a lot of gray area, as Blake Beavan and non-roster invitees Scott Baker, Randy Wolf and Roenis Elias are also scheduled for starts in upcoming days, though no one has been even tentatively listed yet for the final two Cactus League games on March 28-29, before the team breaks camp.
The club has those seven healthy starting canddiates and will regain Hisashi Iwakuma (sprained finger), Taijuan Walker (sore shoulder) and Brandon Maurer (sore back) sometime after the first few weeks of the regular season if all goes well.
"I like the way things are shaping up," McClendon said. "Some guys are throwing well. Baker had a good game over in the Minor League camp [on Sunday]. So they're starting to pick it up a little bit. The competition is starting to get a little stiff."
Elias is the latest addition, with the 25-year-old Cuban throwing five strong innings on Sunday against the Angels, allowing two hits and one run in his first Cactus League start. He'll get another start, tentatively Saturday in a split-squad game against the Rockies in Scottsdale, on the same day Baker faces the A's in Phoenix.
Beavan is slated to throw Wednesday against the Brewers and again Monday against the White Sox, with Ramirez starting Thursday in Mesa against the Cubs and Paxton lined up for a Friday night game with the Padres in Peoria.
Wolf, like Baker coming back from Tommy John surgery, follows his Tuesday night game against the Padres with another start Sunday against the A's.
Hernandez's next start will come in a Minor League game on Thursday, then he'll get his final spring tuneup on March 25. Paxton is also slated for a Minor League outing on March 27 to keep him on schedule, since the Mariners are off that day.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.