Oakland pitchers ‘all doing what they’re supposed to do’

Oakland’s rotation, pretty much universally pegged as the team’s one potential iffy spot going into the season, hasn’t allowed a run at the Coliseum yet.

Brett Anderson, back for his third stint with Oakland, made his regular-season debut and like new starter Marco Estrada the previous night and Mike Fiers in Thursday’s Coliseum opener, Anderson worked six scoreless innings, helping the A’s down the Angels 4-2. Anderson hasn’t allowed a run at home in 341⁄3 innings, the longest such stretch for the team since moving to Oakland in 1968.

“I feel comfortable here — I’ve pitched here quite a few times,” said Anderson, who began his career with the A’s in 2009.

The last time Oakland got three consecutive scoreless outings of six or more innings was Aug. 24-26, 2005, from Kirk Saarloos, Barry Zito and Joe Blanton.

“They’re all doing what they’re supposed to do,” manager Bob Melvin said of his top three starters. “It’s really good to see.”

Anderson didn’t look entirely sharp initially, walking the leadoff man in each of the first two innings. “That was exactly how I drew it up in my head, walk the first guy on four pitches to face the best player in baseball,” Anderson joked of facing Mike Trout with a man on in the first. “I was around the zone, I just couldn’t make the adjustment to get it back to the plate.”

In the second, Anderson had to work out of a two-on, no-out situation, and in the third, Trout doubled with one out, and Anderson got grounders from Andrelton Simmons and Albert Pujols (with third baseman Matt Chapman making a long throw from beyond the bag).

“The first three innings were grindy, but I made some pitches when I had to and the defense was phenomenal behind me all night,” Anderson said. “After the first three innings, it was more back to normal, with some early groundball outs and quick contact.”

At one point this winter, Oakland had no settled rotation spots until re-signing Fiers and Anderson and adding free-agent Estrada, but top pitching prospect Jesus Luzardo is out for the first two months or so of the season. Frankie Montas earned the fourth spot with a knockout spring and Aaron Brooks, out of options, is in the fifth spot.

“Any time a guy has a good start you want to go out and try to replicate it as well as possible,” Anderson said, adding of Montas, “Now we’ve got a young fireballer going with the best stuff of any of us.”

Saturday evening, Mark Canha got the start in center and he belted his first homer, a two-run shot off right-hander Felix Peña out to left with two outs in the fourth. He emphatically tossed his bat, as is his bat-flippin’ wont.

“That’s kind of his thing,” Melvin said. “It ends up being the biggest hit of the game . ... He brings a lot of energy, and he’s really made himself into a nice player and a versatile player.”

Canha was looking at a great deal more playing time over the next month or two when the team lost Matt Olson to a broken hamate bone, but with a preponderance of right-handed hitters, the A’s dealt for switch-hitting Kendrys Morales, who will platoon at first with Canha.

Morales walked to open the fourth, and with two outs, Canha placed a 2-1 fastball into the seats above the scoreboard in left. Entering the night, Canha had a .240 career average vs. right-handed starters, .237 vs. lefties, and 23 of his 42 career homers now have come off righthanders.

The A’s didn’t get their first hit off Peña until, with two outs in the third, No. 9 hitter Josh Phegley banged a single to center. Robbie Grossman followed with a hit to right, and Peña hit Chapman to load the bases. Stephen Piscotty drilled a 3-1 fastball up the middle, sending in the Oakland’s first two runs.

The Angels didn’t score until the eighth, when David Fletcher reached base on an error by Jurickson Profar, Zack Cozart doubled and Trout provided a sacrifice fly, ending J.B. Wendelken’s streak of 172⁄3 scoreless innings. Simmons drove in Cozart with a single, and closer Blake Treinen took over for a five-out save, his first of the season.

Susan Slusser is a San Francisco Chronicle staff writer. Email: sslusser@sfchronicle.com Twitter: @susanslusser