The right-hander won't have too many more chances to turn things around before the playoffs. The first comes on Sunday afternoon, when the National League West-leading Giants finish their three-game series against the D-backs at Chase Field.
San Francisco will be going for a sweep against Arizona, which is sending rookie Patrick Corbin to the mound to defend its dwindling playoff hopes. The D-backs remained 4 1/2 games out the second NL Wild Card spot after losing on Saturday.
Vogelsong posted a 2.71 ERA in 30 games for the Giants last season and owned a 2.27 mark over his first 21 outings this season. But that number has swelled to 9.57 over his past six starts, paired with six home runs and a .371 opponent batting average.
On the positive side, Vogelsong still has compiled a 32-to-7 strikeout-to-walk ratio during that period and was encouraged by how he finished his last outing. On Monday at Coors Field, the Rockies reached him for three runs in his first two innings but only one more over the next three.
"I felt like I actually got a little bit better as the game went on, so that's a good sign," Vogelsong said following the outing. "I felt pretty good about the way I threw the ball the last couple innings, so I just have to try and go off of those."
Corbin (5-7, 4.19 ERA) also has struggled of late, going 0-3 with a 6.00 mark in his last four starts. On Sunday at San Diego, he gave up three runs on six hits in 5 1/3 innings, including a Chris Denorfia home run.
"Patrick threw the ball fine. Made a couple mistakes, the one to Denorfia," D-backs manager Kirk Gibson said. "Overall, a pretty solid performance."
Giants: Posey unfazed by position switching
Buster Posey started at first base for the second time in three games on Saturday and for the 24th time this season, as the Giants have sought to give him breaks from behind the plate.
When it comes to performance at the plate, position hasn't made much difference for Posey. Entering Saturday, when he went 3-for-4 with a double and a home run, he was hitting .327 with a .946 OPS at catcher and .346 with a .959 OPS at first.
Despite catching less than full-time, Posey leads the Majors in both stolen-base attempts against (80) and runners thrown out (28), for a 35 percent success rate.
"I don't think they're trying to run on Buster as much as they're trying to run on the pitcher," manager Bruce Bochy said. "He's very respected with his arm and his release."
D-backs: Young progressing toward return
Center fielder Chris Young hasn't started a game since Sept. 3, the result of a right quad strain. He has pinch-hit in both of the past two games and now could be close to making it back to the starting lineup.
"C.Y. ran really good. I thought about playing him tonight, but I talked to the trainers," Gibson said before Saturday's game. "He was on the bases with the spikes on and he got a little fatigued, which he's not used to. The smart thing to do is wait and see. The earliest he'll be back is after the off-day on Tuesday."
Injuries have limited Young to 93 games this season, and he has hit .227 with 14 home runs and a .740 OPS.
The D-backs are unsure if veteran infielder Willie Bloomquist will return this season from a back injury that has limited him to 10 at-bats since the beginning of August and none since Sept. 3. Bloomquist, whom Gibson called "the spark plug to our team," is expected to be fine for 2013.
After Sunday, the teams have one more series, from Sept. 25-27 in San Francisco.
Vogelsong has a 6.10 ERA in two starts this season against the D-backs, while Corbin owns a 3.75 mark in two outings against the Giants.