SAN FRANCISCO -- Emphasizing progress instead of perfection is helping Barry Zito cope with his 0-4 start.

Zito's record continued to dip Wednesday as the Giants mustered only three hits off Arizona ace Brandon Webb and fell to the Diamondbacks, 4-1. The decision ended a 5-5 homestand for the Giants, who begin a three-city trip Friday in St. Louis.

Zito's competence was no match for Webb's excellence. This didn't please the Giants partisans, some of whom booed as Zito walked the bases loaded in the second inning to set up Webb's two-out, two-run bloop single that loomed large in the outcome.

But Zito, who's 13-22 lifetime in March and April and owns winning records in every other month, insisted that he can sense that his winning form is within reach.

"I can't focus on the record at this point, but I feel good and the ball's coming out of my hand better every game," Zito said. "Going against Webb, I didn't have much margin for error and those walks in the second inning were the difference. I know that I have good stuff in me. I know it's going to surface eventually."

D-backs left fielder Eric Byrnes, whose fifth-inning RBI double was his third hit off Zito in 18 career at-bats, expressed confidence in his former Oakland A's teammate.

"I think Zito's going to be fine," Byrnes said. "I don't think there's hiding the fact that his velocity's down a little bit, but he competes and he still knows how to pitch. ... He's still a guy you're going to have to bring your 'A' game against to have success."

Byrnes, a native of Redwood City, Calif., who grew up rooting for the Giants, urged fans to be patient with Zito, whose $126 million contract invites ridicule.

"I can understand the people's frustrations and I can understand Barry being frustrated," Byrnes said. "But the great thing about him is he's not going to be one of those guys who are going to get a big contract and be content. He's going to continue to work and find a way to get better. I know him as a friend. This guy cares as much, if not more than, any player I've ever played with. I really believe some of his struggles are temporary."

Zito's troubles were indeed fleeting in the second inning, but they lasted long enough to allow the D-backs to capitalize.

Zito began his laborious 38-pitch inning by walking Conor Jackson and Mark Reynolds on 3-2 pitches and issuing a four-pitch walk to Justin Upton.

"I think my timing got off a little bit," Zito said. "There are a couple of mechanical keys you always focus on to get the ball down, and it went haywire for a little bit."

Zito recovered by slipping a called third strike past Chris Snyder, who fouled off four 3-2 pitches. After retiring Stephen Drew on a fly to shallow right field, Zito appeared bound to escape the inning unscathed. But Webb poked an outside 2-0 fastball into right-center field to score Jackson and Reynolds.

"He couldn't have thrown it out there any better-placed," Zito said. "If that happens 10 times, it's probably a fly ball at somebody eight or nine times."

Zito lasted six innings against the Major League's highest-scoring offense, allowing all of Arizona's runs (including one unearned) and five hits. He did not yield a home run for the first time this season. But it marked the third time he had faced an opposing No. 1 starter, following encounters with the Dodgers' Brad Penny and the Brewers' Ben Sheets. The Giants scored once in 23 2/3 innings off those pitchers.

Webb (4-0), who worked eight innings, sustained that dominance by retiring eight of nine hitters on ground balls with his devastating sinker after Eugenio Velez's fourth-inning RBI double. But the Giants actually brought the tying run to the plate in the seventh inning against Webb, who walked Randy Winn and John Bowker. But although Bowker walked on four pitches, Jose Castillo swung on the first pitch and popped up for the second out. Webb then retired Rich Aurilia on a fly to left.

Manager Bruce Bochy refused to fault Castillo for his impetuous swing.

"He can tie the ballgame," Bochy said. "He's got doubles power and he can hit the ball out of the ballpark. You want him looking for a pitch he can drive to do some damage. You've got a guy hitting in your sixth hole and you certainly don't want him taking one right there. The ball just ran in on him."

All things considered, finishing .500 on the homestand after a season-opening 1-5 trip was tolerable for the Giants.

"I think our play has picked up," Bochy said. "We had some lapses, but we're getting more consistent with our defense and the team is developing confidence."