"Hopefully this will be the last time I'm called back up," said Webb.
Webb said he used his 17 appearances at Triple-A Portland, where he was 1-0 with a 0.87 ERA, to polish his changeup, a pitch he was hesitant to use against Major League hitters.
"It was a good time for me to work on things that you can't work on or don't want to when you're having success up here," he said, "so you go down and try to get even better."
The rookie right-hander said he now feels more comfortable mixing in the change-of-pace pitch with his fastball, slider and curveball.
"If everybody is sitting on something hard," Webb explained, "they're comfortable at the plate, so anything that makes the hitter less comfortable you can use as an advantage."
Stewart, meanwhile, had planned to meet the Padres for their weekend series in San Diego. Yorvit Torrealba's balky back had another idea.
With Torrealba day-to-day, Stewart joined the Padres before Wednesday's 5-2 loss to the D-backs. He was available off of the bench while Nick Hundley caught and hit sixth.
The 28-year-old Stewart, who previously made big league appearances with the Rangers, White Sox and Yankees, said that because he wasn't on San Diego's 40-man roster, he didn't expect the call up.
"It was a welcomed surprise for sure," he said.
Stewart batted .248 with seven home runs and 39 RBIs in 85 games for Triple-A Portland. He gives the Padres a third catcher.
"If they have to pinch-hit for a [catcher] earlier in the game ... [and] that second guy gets injured. It makes [Black's] managing more flexible, and hopefully I can help out in more ways being the extra guy just in case."
To clear a 40-man slot for Stewart, the Padres designated for assignment right-handed pitcher Cesar Carrillo, who had spent the entire season at Triple-A Portland.