Trout's blast to center field in the eighth inning against reliever Travis Blackley came during a 10-4 triumph by the Athletics at the Coliseum, forged largely by a large fellow from the previous generation.
Unflappable Bartolo Colon, at 39, was the star of this show. He extended to a career-best 22 1/3 his string of scoreless innings before surrendering an unearned run in the seventh.
Colon was touched for four hits in his seven innings, walking none with five strikeouts. Of his 93 pitches, 72 were in the strike zone.
"He's a bulldog," Angels slugger Mark Trumbo said with admiration. "He comes right after you, and as a hitter, you appreciate that."
Facing manager Mike Scioscia's troupe for the seventh time since leaving the club's embrace in 2007, two years after winning the American League's Cy Young Award, Colon schooled Angels young and old with his mastery.
The A's, meanwhile, were having a ton of fun offensively at the expense of C.J. Wilson and the Angels' bullpen. Home runs came off the bats of Jonny Gomes, Derek Norris, Adam Rosales and Josh Reddick as Wilson fell to 9-8, matching Colon's record. Erick Aybar also homered for the Angels.
Since his modest 6-8 final season in Anaheim, Colon is 4-1 against the Angels, yielding 10 earned runs across 49 2/3 innings for a 1.81 ERA.
He doesn't act like a guy who would hold a grudge, but his work against his old team suggests the man from the Dominican Republic summons added motivation when he sees red.
"I have good preparation when I'm going to pitch against a team I know like the Angels," Colon said. "I know they're going to be aggressive, play hard all the time and never give up. They're battlers, so you have to battle against them.
"This was an important game for our team. We've been losing three games in a row and we needed to win this one. It doesn't matter how you win."
Trumbo sees Colon as a pitching model, worthy of study.
"I think teams should have their young guys watch him, to see how he does it," Trumbo said, having collected one of the four hits with a first-inning single through the middle.
"He challenges you. He throws 90 percent-plus fastballs with good movement. He bores it in on your hands and then works it off the plate. His two-seamer looks like a ball and then comes back across the corner.
"You have to stay in an aggressive mindset with him, because you don't want him getting you in a bad count."
Before bombing his homer with his parents in the crowd of 15,458, Trout had struggled against Colon, striking out in his first two at-bats.
"He was running his fastball in and out, keeping you off balance," Trout said. "You can't lean on him, and you can't give up on that pitch that comes back over the plate.
"He's tough. It wasn't a good night for us, but I did get to have my folks see my 20th homer, so that was nice."
Trout was not aware of having become the youngest player in history to combine at least 20 homers with 30 or more steals. Houston's Cesar Cedeno did it at 22. He homered off of reliever Travis Blackley.
Trout is 36 for 39 in thefts, leading the league in that category as well as batting average at .346. His on-base percentage is .409, and he's slugging .601.
"All that talent and only 21 years old ... it's amazing," a gracious Colon said. "I want to congratulate him for his 20th home run on his birthday."
If the A's insist on not going away, much of the credit will go to Colon. His relaxed demeanor has to be an elixir to a team playing closer to its physical potential than any in the sport.
This is exactly what general manager Billy Beane had in mind when the A's signed Colon following a solid 2011 season with the Yankees.
"It has all year," A's manager Bob Melvin said when asked if Colon's presence has been a benefit to teammates. "That's one of the reasons Billy targeted a veteran like him. He really enjoys the game -- especially on game day. You see a lot of pitchers on game day who can be tough to talk to, but not Bartolo.
"A lot of our younger guys can learn from that. His attitude has rubbed off on a lot of our young pitchers."
Colon is one of two Cy Young Award winners in Angels history, joining Dean Chance.
This drubbing pulled the A's ahead of the Angels by a half-game in the American League Wild Card race, tied with Baltimore a game behind Detroit. The Rangers, having won in Boston, are 5 1/2 ahead of the A's and six in front of the Angels in the AL West.
Colon gave up two singles in the first inning and nothing until the seventh, when an error by second baseman Jemile Weeks on Kendrys Morales led to a pair of unearned runs on two-out singles by Aybar and Maicer Izturis.
Morales, Aybar and Izturis are three of six Angels who were Colon's teammates in 2007, along with Howie Kendrick, Ervin Santana and Jered Weaver.
"That was a while ago," Colon said, grinning.
He's not getting older. He's getting better.
Lyle Spencer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.