Catcher John Jaso's three-run triple in the fourth wiped away a 2-0 Angels lead, and after Los Angeles roared back in the fifth on Wells' three-run homer off Ryan Cook, the A's responded with just as many runs in the bottom of the inning, courtesy of RBI hits from Josh Reddick and Brandon Moss.
Trout led off the game with a double off A's righty Dan Straily and came around to score on Howie Kendrick's base hit. Trout also collected singles in the second and fifth innings to raise his spring average to .417.
It was another leadoff double in the second, this time off the bat of Andrew Romine, that helped the Angels get on the board once again, after Romine moved to third on a groundout and scored on Scott Cousins' sacrifice fly.
Straily lasted 2 1/3 innings in his second start of the spring, giving up two runs on four hits with no walks and two strikeouts. The right-hander, who has surrendered four runs and six hits spanning 3 2/3 innings of Cactus League play, was pleased with the progress he made on inside fastballs to left-handers on Monday.
"That's kind of what [pitching coach] Curt Young and I were talking about before the game, so I can say I got a little bit better today," said Straily, who has allowed four runs and six hits this spring. "It wasn't the greatest outing, but I was working on stuff, trying to get better."
"I thought he pitched better than the numbers show," manager Bob Melvin said. "He hung a couple of pitches, maybe a couple of two-strike breaking balls he threw that got a little more plate and were up a bit, but I thought, overall, his stuff was good."
Angels starter Jason Vargas, meanwhile, was nearly perfect in his two innings on the mound, walking one with one strikeout in his debut for the Angels, who acquired his services from the Mariners in exchange for Kendrys Morales on Dec. 19.
"I mainly threw fastballs, and for the most part they were strikes," said Vargas. "I threw a couple decent changeups, but other than that I was just trying to pound the strike zone with fastballs."
The A's sent 10 men to the plate in the eighth, scoring six runs largely off the struggles of Chad Cordero, who allowed five hits in two-thirds of an inning.
Up next: The Angels return to Tempe Diablo Stadium on Tuesday to take on the Reds at 12:05 p.m. PT. Josh Hamilton is expected to make his second appearance of the spring in the outfield.