Whalen was named the starter for Saturday night's Cactus League game against the Angels in place of Felix Hernandez (forearm), Greg Johns of MLB.com reports.
It will be the 23-year-old's first Cactus League start of the year, following a two-inning scoreless stint against the Dodgers in his spring debut on Feb. 25. Whalen endured a rough 2017 in which he cut his season short in July due to anxiety and depression, but he's been praised by Mariners staff early in spring training with what appears to be a renewed and brighter outlook. The right-hander's first two regular-season major-league stints have been rocky (6.57 and 6.14 ERAs with the Braves and Mariners, respectively), but he'll look to secure a role on the big-league staff this spring.