ANAHEIM -- No outcome on Friday was going to change the A’s encouraging outlook on Ken Waldichuk’s future after what has been a successful second half. But for the last time he would take the mound in 2023, the left-hander would have preferred to enter the winter on a better note.

Making his final start of the season, Waldichuk allowed five runs (four earned) on seven hits and three walks with three strikeouts across five innings in Oakland’s 5-1 series-opening loss to the Angels at Angel Stadium.

“It was a grind for Ken,” said A’s manager Mark Kotsay, noting that Waldichuk’s fastball velocity was down nearly 2 mph from his season average of 93.4 mph. “Overall, with what he had and what he went out there with, he battled. … Not the way he wanted to finish up, but I don’t think that dampens the progress and the way he’s pitched the second half.”

Waldichuk retired nine of the first 13 batters he faced through three scoreless innings. Even after a three-run fourth by the Halos that was largely the result of JJ Bleday’s error in left field that plated two runs on a single by Nolan Schanuel, Waldichuk still had a shot at a decent final line. But with two outs in the fifth, the left-hander fell behind in the count to Mickey Moniak and left a fastball up over the middle that was crushed over the wall in center for a two-run blast.

“Not too pleased with it,” Waldichuk said of his outing. “I gave up three free passes. It’s crucial for me to stay in the zone and not do that. I feel like when things start to get out of hand, that’s usually the reason why. It’s not one to be happy with, but it will be good motivation for me going into this offseason.”

Waldichuk’s first full season in the Majors was a tale of two halves. The rookie entered ‘23 rated the A’s top overall pitching prospect by MLB Pipeline, but struggled to a 6.85 ERA through nine starts and was demoted to the bullpen.

Heading into Friday’s start, Waldichuk was putting together a strong finish, carrying a 3.80 ERA in 13 games (10 starts) since the All-Star Break. He attributed the turnaround -- which likely secured him a spot in the A’s starting rotation to begin next season -- to the temporary move to the bullpen, which helped him both reshape his mentality on the mound as well as refine his arsenal of pitches.

“My first half, I don’t think there’s another word for it but atrocious,” Waldichuk said. “I was staring at a 10.00 ERA after the first two months. Second half, I felt pretty good. I felt like I learned a lot, especially from my time in the bullpen, about just how to attack hitters. Even with my [velocity] being down this past month, I think if I come back with better stuff next year, I think I’ll see some success.”

While the overall 5.36 ERA may not stand out for Waldichuk, there are some positives to take away from his year. As of Friday night, his 132 strikeouts put him fourth among Major League rookies and tied with Tim Hudson (1999) for fifth-most by a rookie in Oakland history.

One area Waldichuk will look to improve for next season is limiting walks. Entering Friday, his 4.5 walks per nine innings was fifth-worst in the Majors this season among pitchers with at least 130 innings.

“Being in the zone is the biggest thing,” Waldichuk said of his takeaways from the season. “Know how to attack guys and figure out what they’re looking for based on reading them and knowing what to throw them based off that.”