OAKLAND -- The A's got a taste Monday of what makes Los Angeles Angels rookie Mike Trout a strong Most Valuable Player candidate.

They also learned why right-hander Jered Weaver owns an astounding 15-1 record.

A 4-0 loss was a demoralizing way for the A's to open a three-game series against a team they're neck-and-neck with in the American League West race and the wild-card chase.

They mustered just four hits against Weaver, who faced three batters over the minimum and lowered his ERA to 2.13.

Trout helped set the tone, reaching base four times from the leadoff spot, stealing three bases and adding a run-scoring single off A's starter Jarrod Parker (7-6).

It was a tidy summation of Trout's game. He leads the league in batting average (.348), runs (86) and stolen bases (36). How could life get any better for the Angels' young superstar?

Trout celebrates his 21st birthday Tuesday.

"He fast," A's catcher Derek Norris said. "It was kind of cool to be out there and see him play. Unfortunately, he's on the other team."

Parker gave up a career high-tying nine hits over 62/3 innings and has a 5.95 ERA over his past six starts.

He surrendered Erick Aybar's RBI single in the second to break a scoreless tie. Two batters later, Trout hit a 3-1 pitch to right field for another run-scoring single.

Trout aided the Angels' other rally in the seventh with a grounder to first that advanced runners to

Parker also had high praise for Trout.

"He wreaks havoc out there," he said. "He's scary, and he's only going to get better."

The A's faithful can only wonder what it might have been like had Oakland selected Trout with its first pick in the 2009 draft. They were one of 21 teams that passed on the New Jersey high school standout before the Angels scooped him up with the 25th overall pick.

"They contacted me (before the draft), but I don't know how high they were on me," Trout said.

The A's are believed to have had Trout high on their draft board, but they selected USC shortstop Grant Green with the 13th overall pick. Green has yet to crack the majors, but the A's consider his hitting close to major league-ready, and a September call-up is a possibility.

The A's have tried Green in the outfield and at third base along with shortstop, and now they want him to get an extended look at second base.

The night's most entertaining play also involved Trout. He tried extending a single into a double in the fifth, but A's right fielder Josh Reddick nailed him at second.

It was a close play, and Trout was gesturing and yelling at second-base ump Bill Miller before he even finished popping up from his headfirst dive.

For Reddick, it was his major league-leading 13th outfield assist.

That was the extent of the highlights for the A's, who have lost three straight and six of nine. They held at least a share of a playoff spot for 16 straight days but now trail the Angels by a half-game for the second of the A.L.'s two wild card spots.