It's pretty odious to pick apart individual decisions of an at-bat, really. As in, "He should have/have not (swung)(taken) that pitch." It's impossible to get that dogmatic without knowing what the hitter was looking for, and what the pitch looked like coming to the plate.
That written, Alex Avila led off the bottom of the seventh, and he worked a 3-1 count against Tim Lincecum. The reason that Lincecum is in the bullpen ... well, there are a lot of reasons, but the main one is his command. He's walking more hitters now than he ever did in the majors.
But on the 3-1 pitch, Avila swung, chopping it right back to Lincecum, who ran it to first unassisted for the first out of the inning.
If he takes the pitch, maybe Lincecum gives up a leadoff walk on the following 3-2 pitch, and the inning goes quite differently. As it happened, though, Omar Infante flew out for the second out, and after an Austin Jackson walk -- see? see? -- Quintin Berry chased a series of changeups to end the inning.
Heading into the 8th, the Giants are still up, 2-0.