MESA, Ariz. -- His three plate appearances will hardly make a highlight reel, but Giants outfielder Mike Yastrzemski was mostly pleased with how he felt in his first Spring Training action against the Athletics on Wednesday at Hohokam Stadium.

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The 33-year-old, who is working back from a left shoulder impingement suffered in the offseason, served as the Giants’ designated hitter and went 0-for-2 with two flyouts and a walk. Both Yastrzemski and manager Bob Melvin noted the outfielder’s final at-bat, a left-on-left matchup with A’s southpaw Scott Alexander. Yastrzemski was able to stay on a breaking ball tailing away and lift it to left field.

“I got beat a little bit,” Yastrzemski said, “but the fact that I’m executing what I’m trying to do on day one is really promising for me and it feels really good.”

Yastrzemski has been able to swing all spring, but he is still going through a throwing progression as he looks to return from his shoulder ailment. He suffered the injury in December -- “Your guess is as good as mine” as to its cause, he said -- but this week he transitioned to throwing every day. Wednesday was his first day throwing at 200 feet, “to get air under the ball versus throwing intently from a shorter position.” So far, he has not battled any lingering soreness.

The veteran remains on track to be ready for Opening Day and is expected to be the lefty-hitting side of an outfield platoon with Austin Slater, who is also working back from an injury this spring. Yastrzemski has a career .821 OPS against right-handers compared to a .690 mark against lefties, although he hit southpaws well his first two years in the Majors. That’s why Melvin found Yastrzemski’s fifth-inning flyout encouraging.

“He stayed on it a little bit and hit the ball to left field, which he has the ability to do,” Melvin said. “In the past, he’s hit lefties really well. Just not the last couple years. I know it’s something he’s going to be working on this spring.”

Howard roughed up

Melvin’s tone after San Francisco’s 7-4 loss was terse, and though right-hander Spencer Howard was not the main target of his annoyance, the non-roster invitee did kickstart the scoring bonanza that so rankled the manager.

One of many pitchers vying for a spot in a rotation beset by injuries, Howard started the game and allowed back-to-back home runs before retiring the next three hitters in his lone inning of work. The A’s also smacked a third home run and two triples to hang seven runs on the board before the fifth inning was over.

“When the first two guys hit homers, it gets your attention a little bit,” Melvin said. “We’re giving up way too many runs early in games here, putting ourselves in a hole. We’re scoring some runs but we’re giving up way too many. It’s not a great feeling.”

Howard is in camp on a Minor League deal. A former top prospect with the Phillies, he was traded to the Rangers at the 2021 trade deadline as part of the package for Kyle Gibson. He’s struggled with injuries and performance in the Majors -- he owns a career 7.20 ERA in 115 innings -- and last year was flipped to the Yankees at midseason, where he pitched in the Minors before being released.

Roupp impresses

Melvin watched Wednesday morning as Landen Roupp threw a live batting practice session at Scottsdale Stadium before the team’s workout. The manager came away impressed with Roupp, a right-hander who ranks No. 15 in San Francisco’s system according to MLB Pipeline.

“He’s got a really good arm,” Melvin said. “It’s an exciting pitcher.”

Roupp had a 1.74 ERA with Double-A Richmond last year but threw only 31 innings as he battled back issues. Because of workload concerns and their injury histories, the Giants have delayed the start of spring for both Roupp and fellow pitching prospect Carson Whisenhunt. Wednesday was Roupp’s first live BP session, while Whisenhunt has yet to face hitters.

Neither is in the mix to make the Opening Day rotation, but the Giants are counting on both as pitching depth later in the year.

“[They’re] guys that could be impactful as the year goes along,” Melvin said, “and might be as talented as any of the guys we’ve had.”