ANAHEIM -- With an eye toward 2022, the Angels have utilized an incredible amount of pitchers making their Major League debuts this season.

Lefty Jhonathan Diaz was the latest on Friday, becoming the 11th rookie pitcher to make his MLB debut with the Angels this season. Diaz, though, struggled, as he lasted just 1 2/3 innings in a 5-4 loss to the A’s in the series opener at Angel Stadium.

"I liked him but he just didn't throw strikes,” Angels manager Joe Maddon said of the rookie's outing. “The first hitter, he hits [Josh] Harrison on the foot on an 0-2 count, and sometimes that can set the tone. He could not get to the zone with any kind of regularity. But it's not like they just went out there and pummeled him. The sliders were good, the changeup was good. We just lost the game based on walks."

Diaz was slated to start with Triple-A Salt Lake but saw his contract selected to start against Oakland, as two-way star Shohei Ohtani’s scheduled start was pushed back two days to Sunday because of arm soreness. Diaz, who was signed as a Minor League free agent in the offseason, had posted a 4.01 ERA with 92 strikeouts in 76 1/3 innings with Double-A Rocket City and Salt Lake.

“I felt a little nervous going into the game but after the first batter, it kind of went away,” Diaz said through an interpreter. “I reached my goal of getting here, but now it’s about maintaining it.”

The 25-year-old joined Austin Warren, Andrew Wantz, Kyle Tyler, Chris Rodriguez, Elvis Peguero, Oliver Ortega, Jose Marte, Janson Junk, Reid Detmers and Cooper Criswell as Angels pitchers to make their debuts in 2021. Such a focused youth movement allows the Angels to get a chance to see some of their young pitchers heading into next year.

Diaz, however, had trouble with his command, hitting Harrison to begin the game and walking four (among the nine Halos pitchers surrendered on the night). The lefty loaded the bases with one out in the first but escaped the jam, striking out Chad Pinder and Matt Chapman on sliders to notch the first two whiffs of his career.

“My best pitch is my fastball, but my second-best pitch is my slider, especially when I have command of it,” Diaz said. “I was able to locate it pretty well to get out of that inning.”

But he wasn’t quite as fortunate in the second, allowing the first four batters to reach, including Harrison, who brought home a run with an RBI single. After he gave up a run on a sacrifice fly to Matt Olson, he was removed for Tyler. Tyler promptly hit Mark Canha to load the bases again, but got Pinder to fly out to end the inning.

Tyler, making his fourth career appearance, remained in the game and threw 2 2/3 solid innings, allowing one run on three hits, to help keep the Angels in the game. He's posted a 0.93 ERA in 9 2/3 innings this year.

"He kind of fought his way through it,” Maddon said of Tyler. “He didn't have the same look as the last couple times but I give him credit. He was not flustered in any way and kept making adjustments even though he didn't have his slider working. His cutter was there, and I just like his makeup a lot."

The Angels took the lead with a four-run second keyed by two errors from the A’s, a solo homer from Kurt Suzuki and a two-run single from David Fletcher, who also turned an impressive double play in the fifth.

But the Angels couldn’t hold the lead, as Marte gave up two runs in the sixth in his return from being on the injured list with COVID-19. Suzuki was charged with two costly passed balls, including one that allowed the go-ahead run to score.

"Marte has really good stuff and as a catcher, sometimes if you miss your location with a fastball it's really tough,” Maddon said. “But yeah, we want to win games, and I think that was evident tonight. I didn't like the way we played, I loved the way we played and we did it with a lot of freshman pitchers. You're going to see a lot of guys get opportunities, but there's no less desire to win the game."