Manaea’s had better days

MESA, Ariz. — The A’s young starting pitchers had an impressive stretch to open the Cactus League season.

At least until Sean Manaea took the mound Saturday.

The Indians took virtual batting practice against the left-hander, who coughed up five runs (four earned) on five hits (four doubles) in 12⁄3 innings and threw just two firstpitch strikes.

Manaea said a mechanical issue caused command issues with his changeup. As for his fastball? “I was just throwing it right down the middle,” he said.

It was a rare clunker for the rotation, which before Saturday had posted a 2.63 ERA — four earned runs in 132⁄3 innings — and hadn’t yielded a first-inning run.

Kendall Graveman had two scoreless outings, Sonny Gray one. Three of the runs were yielded in one inning by Jesse Hahn, who has started twice. Jharel Cotton gave up the other run.

“It starts with Sonny,” manager Bob Melvin said. “When your lead guy’s pitching well, everybody kind of feeds off that. I think we have the makings of a good, young rotation, and we have depth in the system, too.”

As for Manaea, Melvin said, “It was one of those days. He’s not a guy you worry too much about.”

That 2.63 ERA excluded Manaea’s first outing, which came in relief Monday. He tossed two scoreless innings.

So overall, the early signs are encouraging for a rotation that last year ranked 14th in the American League in ERA (4.84), ahead of only the Twins, and the highest for Oakland since 1999.

Smolinski will DH: Outfielder Jake Smolinski will play his first exhibition Sunday as the designated hitter. He’s still not throwing after opening spring training with a shoulder ailment.

“I’ve been doing everything but throwing,” said Smolinski.

Briefly: Santiago Casilla finally will join his new team Sunday. The word from the Dominican Republic’s World Baseball Classic team is that Casilla will miss the first round of the WBC, at least . ... Third baseman Matt Chapman was scratched with an unusual injury. He stubbed his toe on a chair and cracked a nail . ... Ryan Madson will pitch in his first game Tuesday. He has had arm soreness . ... Another reliever who is being eased in, Sean Doolittle, will throw to hitters Sunday . ... Tommy John patients Chris Bassitt and Felix Doubront continue to throw off a mound but no breaking pitches.