Guzman (first base) and Velez (left field) batted sixth and seventh Monday night, as manager Bruce Bochy sought to bolster a struggling lineup. In the Giants' first 10 games after the All-Star break, the offense averaged just 2.3 runs a contest, down from their June average of 4.3.
"We're hoping Guzman can help provide some offense here," Bochy said. "[He and Velez] have been swinging the bats well, and we're facing some lefties coming up in the next two series. Hopefully they'll be a shot in the arm for the offense."
The Giants opposed Pirates lefty Paul Maholm on Monday night at China Basin and will face left-handed Zach Duke on Wednesday to conclude the series. Both Guzman and Velez batted above .340 against lefty hurlers in the Minor Leagues this season.
Guzman collected one hit in his first 10 Major League at-bats in a four-game stint in May. He returned to Triple-A -- not seeking to make changes but simply to amp up his bat -- and was riding a 26-game hitting streak (raising his season average to .336) when he got the news Sunday on the telephone.
"I'm going to give my best for the team when I go the plate," said Guzman, who was all smiles as he embraced some familiar faces. "I believe in these guys."
Velez arrived to help "the guys," too. The switch-hitting utility man made the Opening Day roster but batted .194 in limited action before being optioned to Fresno. He offers the Giants another backup infielder, with Rich Aurilia (toe infection) on the 15-day disabled list and Edgar Renteria (sore elbow) trying to reach full strength, plus another option to play the outfield as Aaron Rowand (torn forearm muscle) works his way back.
Monday's roster causalities, Bowker and Downs, left the ballpark without speaking to reporters. Bowker batted .156 in 11 games since his July 9 callup, and Downs went 2-for-17 at the plate in his second stint with San Francisco, lowering his season average to .170.
"Matt and Johnny haven't gotten settled in yet and they're going to be nice players," Bochy said. "I've talked about this before; it takes a while sometimes -- and longer for [some] players -- until they get comfortable and settled in to show what they can do. At this point, we needed to make a move to see if we can speed this up a little bit as far as getting this offense going."
Andrew Pentis is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.