Webb held the Padres in check while Chris Young and Stephen Drew hit two-run homers for the Arizona Diamondbacks, who won 4-0 over a Padres club that continued to struggle after firing hitting coach Merv Rettenmund.
Hours before watching the Diamondbacks vault into sole possession of first place in the NL West, the Padres made three trades and fired Rettenmund. Afterward, they released reserve infielder Jose Cruz Jr. They'll need to make two more moves on Wednesday to make room for newcomers Morgan Ensberg, Rob Mackowiak and Wilfredo Ledezma.
"I mean, there's a lot of uncertainty, a lot of guys looking over their shoulder right now," leadoff hitter Brian Giles said. "We still don't have all the guys that we traded for. We've got to find a way to weather all the uncertainty, try to get us a game tomorrow night and get us a series on Thursday."
The Padres, trying for their third straight NL West title, lost for the 11th time in 18 games since the All-Star break.
The Diamondbacks moved atop the division by one game over the Los Angeles Dodgers. The Padres dropped to 1½ games back.
"Anytime you're in first place in the second half, it's meaningful," manager Bob Melvin said. "But there's a lot of teams bunched, including Colorado. One day you could be in first, the next day you're in third, the way it's worked out so far."
It didn't help that the Padres were facing reigning NL Cy Young winner Webb (10-8). He held San Diego to three hits in seven innings while striking out seven and walking two. The Padres got only one runner to third base and two others to second.
"We swung the bats good early off of him, but really had nothing to show for it," Giles said.
Webb didn't induce as many groundouts as normal, "but we expect him to pile up zeros like that," Melvin said.
"My off-speed stuff, I thought, was pretty good," Webb said. "I had seven strikeouts, all on changeups. My location with the fastball was pretty good."
Going into the game, the Padres were hitting .244, tied with the Chicago White Sox for the worst team average in the big leagues. Their .312 on-base percentage is second-worst in the NL and only three teams had scored fewer runs.
Wally Joyner was hired to replace Rettenmund but won't be with the team until Thursday or Friday.
Coincidentally, Rettenmund's firing came two days after the Padres beat the Houston Astros 18-11, scoring 11 runs in the first inning. The Padres put up their highest run total in five years and had a season-high 19 hits.
Facing Webb, though, the Padres were back to their anemic ways. And while they continue to struggle to reach the fences at Petco Park, opponents sure don't.
"A little bit too much Brandon Webb and a couple two-run homers," manager Bud Black said.
Both Diamondbacks homers came on belt-high fastballs from Justin Germano (6-6), who lost his third straight start and for the sixth time in seven decisions.
Drew homered to center field on a 2-2 pitch in the second. Three-time Gold Glove winner Mike Cameron made a sensational effort trying to catch it by leaping and hanging off the top of the fence, but the ball fell just beyond his reach. Conor Jackson was aboard on a leadoff double.
Young made it 4-0 with one out in the fifth when he drove Germano's first pitch 411 feet to left-center. Carlos Quentin was aboard after getting hit by a pitch opening the inning.
Germano allowed four runs and four hits in five innings, struck out seven and walked one. Webb and two relievers combined on a four hitter.
- Arizona LF Eric Byrnes made a sensational leaping and diving catch of Gonzalez's slicing liner to end the first inning and save a run.
- INF Chad Tracy, who has tendinitis in his right knee, probably won't start again until Thursday, Melvin said.