Giving the ball to Matt Cain at home could also provide a boost.
Pence might be in the Giants lineup for the first time Wednesday night when Cain attempts to continue his home success against the New York Mets.
San Francisco (56-47) leads the West by one game over Los Angeles, with third-place Arizona lurking 3 1/2 back.
Trying to gain some separation, the Giants acquired Pence from Philadelphia in exchange for Nate Schierholtz and two minor leaguers prior to Tuesday's non-waiver trade deadline. Pence is batting .271 with 17 homers and 59 RBIs this season, and provides some much-needed power for a Giants team that ranks last in the majors with 62 homers.
"He gives us another bat in the heart of the order and something we need. It's always great to have a chance and bring somebody like Hunter Pence's caliber in," manager Bruce Bochy said. "I got a chance to spend some time around him at the All-Star game last year. Great guy. Fun to watch. Fans are going to love him. He's around all the time.
"He loves the game and it shows."
Pence, who has a .329 average and five homers in 20 games at AT&T Park, will help replace the injured Pablo Sandoval (hamstring) in the lineup and presumably bat fifth behind fellow outfielder Melky Cabrera and catcher Buster Posey.
Cain (10-3, 2.80 ERA) won't mind having another strong offensive presence in the lineup. He has a 2.11 ERA in his last 13 home starts dating back to last season, and he might be better than 6-2 in that stretch if not for some spotty run support.
The Giants scored only one run while he was in the game Friday, when the right-hander allowed three runs in seven innings of a 5-3, 10-inning loss to the Dodgers.
Cain has won each of his last three home starts against the Mets behind a 0.95 ERA.
The Giants have won seven of 10 at home versus New York after Tuesday's 4-1 victory. That snapped an overall losing streak that had reached a season-high five games when they dropped the opener of this four-game set 8-7 in 10 innings a day prior.
The Mets have lost 15 of 19, including each of Jonathon Niese's last four starts. Niese (7-5, 3.86) is 0-2 with a 5.67 ERA in that stretch after going 5-1 with a 2.17 ERA in his previous eight outings.
The left-hander takes the mound after struggling greatly Friday, matching his career high by surrendering eight runs in six innings of an 11-5 loss at Arizona. He also committed a throwing error that scored two of the six runs in the second.
"One of the reasons I left him in is I wanted him to work a little bit," manager Terry Collins said. "I wanted to see if he could get himself into a little bit of a feel, a rhythm, get his release point back and get into sync so he could leave feeling better about himself than he did after the second inning."
Niese is 0-1 with a 2.77 ERA in two starts against San Francisco. He allowed three runs and seven hits in six innings of a 4-3, 10-inning home loss to the Giants on April 20.