PEORIA, Ariz. -- Daniel Mengden is taking less weight and more confidence into the season.

"I see a look in his eye right now," A's manager Bob Melvin said.

Determined to avoid another bout of foot issues and stay healthy enough -- and consistent enough -- to remain in the A's rotation year-round, Mengden dropped 15 pounds this winter and entered camp ahead of schedule.

"I like coming into Spring Training being ready, feeling ready," Mengden said. "I throw more bullpens in the offseason than maybe most guys do."

Conditions weren't favorable for Mengden's Cactus League debut against the host Mariners on Friday; a steady rain accompanied him to the mound, and the results were shaky. He walked his first batter, then surrendered a homer to his next, Mitch Haniger. Kyle Seager tagged him for a one-out double before Mengden buckled down and struck out his final two batters in the 20-plus-pitch inning of an 8-1 A's loss.

Only so much can be gleaned from one outing, but the A's have only so much time to evaluate roster candidates ahead of their season-opening trip to Japan.

Mengden, 26, is considered a heavy favorite to land one of two open rotation spots behind veterans Mike Fiers, Marco Estrada and Brett Anderson, particularly after the way he closed out 2018. Brought back in late August following a month-plus-long stint on the disabled list with a right foot injury, Mengden found himself in the middle of the club's experiment with an opener.

Mengden pitched behind opener Liam Hendriks in four of his final five outings of the year and found his groove after shaky beginnings, giving up four runs (three earned) over two innings in his first try and holding opponents to one run across 13 2/3 innings in his next three outings.

Mengden desires to start games again, but he's also not opposed to an opener. The right-hander's 2018 performance suggests he could benefit from one; Mengden allowed 15 of his 58 runs in the first inning, yielding a .343 opponents average and a 7.94 ERA.

In all other innings, Mengden held them to a .213 average and pitched to a 3.38 ERA.

"Whenever Bob gives me the ball, I'll be ready," he said. "If it's the first, second, fifth, sixth, whatever it may be, I'm here to help the team win. I'm not saying I am a fan or I'm not a fan."

Mengden debuted with the A's in 2016, and they're 16-8 in his starts over the past two seasons. He's been superb over stretches, including a four-start period in May that featured a 25-inning scoreless streak, but he's also lacked consistency -- and health. He was limited to 16 starts between Oakland and Triple-A Nashville in 2017 after undergoing surgery to address a separate right foot issue ahead of Spring Training.

"I think he's got something to prove this year," Melvin said. "This is a guy we really like. He's been through a lot physically, and we've thrown a lot at him. He's been a guy that's come in after the opener, he's pitched really well at times, had some injuries. Coming in fully healthy, I expect Daniel to have a good year.

"Does that mean he's in the rotation for sure? No. It means he needs to earn a spot, but sitting here right now I have a good feeling that he will."

Said Mengden: "I think you should always have the mindset of you have to bring what you have to the table every time because someone behind you is always trying to take your spot. I think it's about just staying healthy and really maintaining the overall strength, mental side and everything."