Jason Heyward belted a solo homer in the first off Ryan Vogelsong and Freddie Freeman added one of his own in the second, quickly giving Atlanta a 2-0 lead.
Unfortunately, that was not enough for Sheets. The Giants failed to score after loading the bases with no outs in the second inning on three infield hits, but in the third, Angel Pagan and Pablo Sandoval each doubled to left for a run; the tying run scored when Sheets fired a wild pitch, allowing Sandoval to score from third.
Further trouble ensued in the fourth. After Gregor Blanco singled to lead off the inning, Pagan smacked a triple to right for a third run and scored on Marco Scutaro's RBI single.
Sheets was relieved with one out in the fifth after a leadoff walk to Buster Posey and Brandon Belt's one-out double. Cristhian Martinez stranded both runners, but gave up Posey's RBI double in the sixth, plating Scutaro.
Vogelsong retired 10 straight hitters following Freeman's homer and didn't allow another hit until the sixth. He was pulled with one out in the seventh after surrendering Freeman's second home run of the game, another solo shot to right.
An opportunity to cut into the Giants lead with a runner in scoring position was snuffed out in the eighth. Atlanta has now lost six of seven.