Erasmo Ramirez will start Sunday's series finale against the A's as planned, and James Paxton has Tuesday's home opener against the Angels at Safeco Field. That lines up rookie Roenis Elias for Wednesday's game, with Hernandez coming back Friday for the first contest of a three-game weekend set with the A's.
With two off-days coming up on Monday and Thursday during Seattle's opening homestand, Young may not be in line to return to the rotation until the Mariners head back out on the road to Texas and Miami the following week.
The decision for McClendon wasn't difficult.
"I think anytime you have a chance to keep your No. 1 on schedule, you keep him on schedule," McClendon said. "To me, that just makes more sense. They're No. 1 for a reason."
As for Young, who signed a one-year deal two weeks ago after being released by the Nationals?
"He'll pitch out of the bullpen, and hopefully we'll try to keep him as sharp as we can," McClendon said. "Then we'll reevaluate in a few days and see where we are."
Young, a nine-year Major League veteran, has started 159 big league games in his career, but he has never pitched in relief.
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.