PHOENIX -- Ryan Vogelsong knows all about overcoming adversity. Unfortunately for him, he has set himself up for a repeat effort.Vogelsong's slide from National League ERA leader to enigma continued Sunday as the Giants fell to Arizona, 10-2, concluding an otherwise successful two-city trip. The Giants captured two of three games here and at Colorado to extend their streak of unbeaten road series to 10 (nine wins, one split). Though their winning streak of four consecutive games ended, they remained poised to clinch the National League West title, a feat they can accomplish with a solid performance during a 10-game homestand beginning Monday against Colorado. The second-place Dodgers lost to St. Louis, preserving the Giants' 7 1/2-game division lead and shrinking San Francisco's magic number for clinching the division to nine. Manager Bruce Bochy has refused to address postseason-related issues until the Giants officially take the division. But if Vogelsong's stunning slump persists, Bochy and San Francisco's braintrust are bound to wonder how much the right-hander can help the club in October. Vogelsong (12-9) allowed the D-backs seven runs (six earned) and five hits while walking four. In a seven-start stretch beginning Aug. 13, he has recorded a 10.31 ERA, contrasting with a NL-best 2.27 ERA in 21 outings before that skid. Bochy, speaking in his distinctive bass, and Vogelsong, answering questions in tones clipped by frustration, formed a postgame chorus in the visitor's clubhouse at Chase Field. Though neither can determine the source of Vogelsong's problems, the right-hander will stay in the starting rotation and attempt to correct his flaws during game competition. "I feel healthy; I feel strong; my stuff's there. I'm just not getting results," said Vogelsong, whose ascent from Triple-A reject to NL All-Star was one of baseball's most compelling stories last year. "... That's why this is getting perplexing, because my stuff's there. This doesn't make much sense to me right now." In fact, Vogelsong struck out five of the first nine hitters he faced. "The good news is that he's healthy and he's shown how well he can throw at times," Bochy said. "He's fighting himself a little bit. He just has to back off a little. I think he's going a little too hard." Bochy employed similar patience this year with Tim Lincecum, who's 6-4 with a 3.33 ERA since the All-Star break but compiled a 3-10 record with a 6.42 ERA before it. Though Vogelsong probably has just three regular-season starts remaining, Bochy believes that he can regain his equilibrium in timely fashion. Vogelsong, he reasoned, has displayed none of the traits of a failing pitcher, such as overall fatigue or deliveries that lack movement. "Every time he goes out there, I feel good about what's going to happen," Bochy said. "I know he's having his down period right now, but he'll come out of this. If I saw something that would make me want to skip him, sure. But his stuff is too good to see what happened today happen. He's one of our guys and I have all the confidence in the world in him right now." Vogelsong appreciated Bochy's faith: "I've been on the other side of what he's talking about, looking over your shoulder every day. That says a lot." The afternoon unraveled for Vogelsong and the Giants as Arizona broke a 2-2 tie with five runs in the fourth inning. Shortstop Joaquin Arias fumbled Paul Goldschmidt's leadoff grounder for an error. One out later, Cody Ransom doubled and Gerardo Parra drew an intentional walk to load the bases. Up came opposing pitcher Patrick Corbin, batting .069 (2-for-29). He grounded a 1-2 pitch inside first base and into the right-field corner for a triple, giving Arizona a 5-2 lead. Vogelsong walked Adam Eaton before being replaced by Shane Loux, who yielded Aaron Hill's two-run double. "Heater up and in. It wasn't even a strike," Vogelsong said, describing the pitch Corbin hit. The Giants averaged 6.2 runs in the first five games of their trip before encountering Corbin (6-7), the rookie left-hander who limited them to two runs and eight hits in a career-high eight innings. Corbin preyed upon the Giants' aggressive approach simply by varying the 93 pitches he threw. "They were just coming out swinging, so I kept my pitch count down," Corbin said. "It wasn't too high, so I wasn't tired or anything like that. It felt great all day." Buster Posey accounted for both of San Francisco's runs, driving in Angel Pagan with a two-out, first-inning single and scoring on Brandon Belt's fourth-inning double. Bochy said that back tightness prompted Pagan's removal from the game in the sixth inning. Bochy expected the leadoff batter and center fielder to recover sufficiently and start Monday night.
Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.