Myers had landed on the 10-day DL after just three games due to nerve irritation in his right arm. He was 3-for-12 at the plate with a home run.
The 27-year-old played three rehab games and homered twice with Class A Advanced Lake Elsinore before the Padres activated him Friday. Hunter Renfroe and Jose Pirela had been getting most of the time in right field for San Diego in Myers' absence.
Webb made his season debut this week and pitched in two relief outings. The 27-year-old took the loss when the Padres dropped a 12-inning game to the Dodgers on Tuesday, but he pitched three scoreless innings and allowed just one hit in Wednesday's game.