The D-backs finally got on the board in the fourth, when Aaron Hill singled and Jason Kubel smacked a two-out homer to left-center off Mike Ekstrom. The blast gave Arizona a 2-1 lead.
One inning later, Cliff Pennington drew a two-out walk, and Adam Eaton followed with his first homer of the spring to put the D-backs up 4-1.
Wil Nieves added a single in the sixth to drive home pinch-runner Jon Griffin and push the D-backs' lead to 5-1.
Pennington finished the home run barrage with a two-out, two-run shot later in the inning.
Josh Collmenter, expected to be the long man out of the bullpen, got the start for the D-backs and allowed one hit over two innings.
A's starter A.J. Griffin matched Collmenter with two scoreless innings of his own.
"He was really good," A's manager Bob Melvin said. "We know that when he's at his best pitching frequently, he's painting, and, boy, he had his paint brush out from the first pitch today."
The A's missed a scoring opportunity in the sixth, when they put runners at second and third with one out against reliever Tony Sipp, who got a flyout and a strikeout to end the threat. They scored three times in the ninth inning, during which D-backs pitcher Warner Madrigal was knocked out of the game after being hit by a comebacker.
Up next for the A's: One day after A.J. Griffin's solid outing, his opponent in the fifth-starter competition gets to answer as right-hander Dan Straily takes the mound for the A's against the Padres at 12:05 p.m. PT at Phoenix Municipal Stadium, and fans can listen to a free exclusive webcast. Chris Young, who left Sunday's game with a quad cramp for precautionary reasons, is scheduled to return to the starting lineup. He's slated to bat third and play right field.