The 414-foot homer, Szczur's second-longest since Statcast™ was introduced in 2015, cut a two-run deficit in half and provided the first run of San Diego's comeback.
"I was just battling," Szczur said. "[Bumgarner's] fun to compete against because you know no matter how he's feeling or how he's doing, he's going to compete. It's a fun at-bat."
Acquired from the Cubs on May 8, Szczur has most often served as a late-inning defensive replacement in the outfield. Saturday was only Szczur's seventh start since June 9, his last multi-hit performance before doing so in the first half's finale against Philadelphia.
After beating Bumgarner with the long game, Szczur used his short game to achieve his second straight two-hit game. He noticed third baseman Eduardo Nunez playing back in the fifth and dropped down a bunt single.
"He's been working so hard," manager Andy Green said. "... He's put a ton of effort into trying to find his swing as he's kind of battled himself since he's been here. But he's a tremendous teammate. People thrive just being around him."
Szczur pestered Bumgarner again in the seventh, drawing a walk off the San Francisco ace. Not only was it Szczur's first time reaching base three times in a game since June 6, but he also matched the number of times he'd reached against Bumgarner in 11 plate appearances coming into Saturday.
His irregular playing time aside, Szczur has continued to work hard as a member of the Padres, enjoying his time with the organization. He said the staff has always been willing to assist him, whether that's through batting practice or pregame outfield work. Szczur has worked on a consistent, repeatable swing, hitting coach Alan Zinter said.
Szczur's performance against Bumgarner raised his average with San Diego from .182 to .203. Although his overall numbers are below where he would prefer, Szczur proved he has the ability to take advantage of his opportunities.
"He doesn't sit there and complain about playing time," Zinter said. "He's always ready. He comes in here and works just as hard as anybody on this team, and he's ready for that opportunity. He doesn't get down. He's always positive. He's always on the fly, ready to go. You can call on him at any time, and you're going to get the best of Szczur.
"It's nice for him to get in the game and get in some rhythm and get a couple of big hits for us."
Szczur hopes Saturday's outing means there are more to come.
"It just helps your confidence," he said. "When you go in the box and you know you had a good day the day before, you're feeling confident and like you can compete and do well against whoever's on the mound."