PHOENIX -- Mike Napoli's easy swing produced a mammoth drive.
Napoli hit the third-longest homer in the nine-year history of Arizona's ballpark, Orlando Cabrera also connected and Ervin Santana won his fourth straight start to lead the Los Angeles Angels over the slumping Diamondbacks 8-2 Friday night.
Napoli's leadoff homer in the third inning traveled an estimated 470 feet and landed in the second row of seats in front of the second-deck restaurant above left field.
"It just happened," he said. "I tried to hit the ball into the gap and it happened to go."
Santana (8-3) worked around six walks, scattering seven hits over six innings. Napoli went 3-for-3 with two RBI and three runs to help Los Angeles win its second consecutive game after dropping three in a row.
"He's doing the job behind the plate first and foremost," Angels manager Mike Scioscia said. "But you're not going to square up a ball any better than he did."
Chad Tracy hit his team-leading 12th homer for the Diamondbacks, who have lost 16 of 18 to fall two games under .500 for the first time since they were 11-13 on April 29.
Arizona has dropped 10 of 11 at home and been outscored 86-26 in the process.
"I know we're a better team than we're showing right now," said catcher Johnny Estrada, who had two of Arizona's 10 hits. "We were clicking in all phases of the game when we were playing well. You can't expect to sustain that for 162 games."
Los Angeles wasted little time jumping ahead against starter Enrique Gonzalez (2-1). Chone Figgins led off the game with a double and, after a two-out walk to Garret Anderson, scored on Napoli's single for a 1-0 lead.
Gonzalez then walked the next three batters, the final two forcing in runs to give the Angels a 3-0 lead.
"You saw the game, man," Estrada said. "Anytime you walk in two runs you're not going to win in the big leagues."
Cabrera homered in the second to make it 4-0. Napoli extended the lead to 5-0 with his long home run.
Tracy cut the lead to 5-1 with a shot leading off the fourth.
Santana ran into trouble in the fifth, walking Conor Jackson with the bases loaded to make it 5-2. But the right-hander retired Shawn Green on a popup and Johnny Estrada on a routine fly to end the threat.
"He was trying to do too much," Arizona manager Bob Melvin said, referring to Green. "He tried to hit the ball out of the ballpark, potentially. I know he wanted to keep the ball off the ground and stay out of the double play. But we need a run in that situation."
Maicer Izturis added a two-run single in the seventh and Adam Kennedy hit a sacrifice fly off Jose Valverde to extend Los Angeles' lead to 8-2.
J.C. Romero, Brendan Donnelly and Kevin Gregg finished with scoreless relief.
Vladimir Guerrero had an apparent home run turned into a double in the fifth. Guerrero hit a long drive to the left-field fence, where a fan attempted to make the catch. Third base umpire Larry Young originally called the ball a home run before the umpires huddled, ruled fan interference and sent Guerrero back to second. Replays were inconclusive.
Gonzalez allowed five runs, four hits and four walks in four innings.
The Diamondbacks are the only team without a win in interleague play. ... Cabrera has reached base safely in a club-record 51 consecutive games, the longest streak in the majors since New York's Alex Rodriguez reached safely in 53 straight in 2004. ... Both Gonzalez and Santana got their first major league hits off each other. ... Before the game, the Angels placed 1B Darin Erstad on the 15-day disabled list retroactive to June 18 with a right ankle injury. Erstad, who also was shelved May 1 through June 11 by the ankle, was replaced on the roster by OF Tommy Murphy. Erstad is hitting .220 with no homers and five RBI in 27 games this season. ... 3B Dallas McPherson was scratched from the Angels' lineup after having back spasms during batting practice. ... Angels RHP Jered Weaver struck out 14 in a two-hitter for Triple-A Salt Lake in a 1-0 win Friday over Sacramento.