TORONTO -- A rotation missing 80 percent of its original members is going to require some tape and glue to keep things together. And while rookie Chase De Jong is helping fill the gaps as best he can, there will be some on-the-job training along the way.
But De Jong is also smart enough to know that no one is going to care if he's young or was pitching Double-A ball just a year ago.
"I've talked to guys that have been around a very long time and they still say they're learning stuff late into their careers," De Jong said Thursday after taking the loss in Seattle's 7-2 setback to the Blue Jays. "So I'm just trying to be a sponge and adapt as quickly as I can. There is a learning curve, but we still have to be up here and compete and do our job.
"And tonight I did a pretty good job my first couple innings and then had that one slip away pretty quickly."
De Jong had two outs with nobody on in the fifth and was working with a 2-1 lead when the wheels wobbled. A pair of walks, sandwiched around Ezequiel Carrera's base hit, loaded the bases for Justin Smoak.
When De Jong hung a first-pitch curve, the former Mariner shot a two-run single over the head of shifted shortstop Jean Segura in to short center field for 3-2 lead. And Toronto left fielder Steve Pearce supplied the back breaker by driving a 1-2 fastball into the left-field seats for a three-run homer that made it 6-2.
"It was a little bit of growing pains tonight," acknowledged manager Scott Servais. "I thought he threw the ball pretty well. He was in a little trouble in the first on some softer hits. But he had two outs and nobody on in the fifth with a 1-2 count, then the walk to Kevin Pillar.
"It's a hard lesson to learn, but you can never let your guard down in the big leagues. He just didn't finish off the inning and then they got something going against him."
De Jong, making his third start in place of the injured Felix Hernandez, fell to 0-3 with a 7.85 ERA in five outings, including two prior relief appearances. But he'd thrown six innings of one-run ball his previous start and again was sailing pretty well until the two-out rally in the fifth.
The 23-year-old right-hander is one of several Mariners pitchers who've been pushed ahead of schedule to fill the hole created by having four starters -- Hernandez, James Paxton, Hisashi Iwakuma and Drew Smyly -- simultaneously on the disabled list.
De Jong relies on fastball command and said he wasn't as crisp as in his previous outing against Texas.
"It escalated pretty quickly," he said. "I think it was four pitches to get those first two outs [in the fifth] and then it got away pretty quickly. The walks hurt."
So did missing a chance to beat the team that drafted him in the second round in 2012, and then traded him to the Dodgers before his eventual arrival in Seattle.
"It was fun," De Jong said. "I got drafted by them. My cousin [Jordan De Jong] got to the big leagues here. It's a city, ever since I started my career, I thought I'd get here and I was excited to be here. Playing against the jersey was very cool, to say the least, but tonight came down to the fact I wasn't as crisp and didn't command the ball as well as I should have."
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.