Giles went 4-for-6, including a bases-clearing double and a three-run homer, and he finished with seven RBIs.
The Padres record for RBI is eight, shared by Nate Colbert and Ken Caminiti.
But this wasn't the first time that Giles has played a major role in a Padres victory this season.
In the Padres' 23 wins, Giles is hitting .345 (29-for-84) with five doubles, three homers, 23 RBIs and 24 runs. He has also drawn 24 walks in those wins, giving him a .500 on-base percentage and a .512 slugging percentage.
In the Padres' 18 losses, Giles has hit only .215 (14-for-65) with three runs, five RBIs, two doubles and one homer. His on-base percentage in losses is .311 and his slugging percentage is .292.
REPLAY: Staked to a 9-0 lead in the top of the first, right-hander Mike Thompson picked up a win in his major league debut against the Diamondbacks on Wednesday in Phoenix.
Thompson was called up from Triple-A Portland to replace Woody Williams (torn calf muscle) in the rotation. The 25-year-old Thompson allowed four runs (three earned) on seven hits over five innings.
Thompson's stay in the rotation could be a bit longer than originally expected. LHP Shawn Estes was expected to return to the rotation around June 1, but that date has been pushed back to mid-June. Estes has been out since he strained the flexor tendon in his elbow in his first start of the season.
Thompson was 5-0 with a 3.70 ERA with Portland before being promoted to the Padres. Thompson was a fifth-round draft pick of the Padres in 1999. Although he was 4-2 with a 3.15 ERA in nine starts with Portland in the second half of last season after being promoted from Double-A, Thompson was released from the Padres' 40-man roster last October, then re-signed as a minor league free agent.