Broadway, a right-handed relief pitcher, entered the game in the seventh inning with the Giants trailing by two and promptly struck out D-backs third baseman Jake Lamb on three pitches.
The 28-year-old, who signed a Minor League contract with San Francisco in January 2014, said he was nervous warming up in the bullpen, but once he stepped on the rubber and fired the first pitch, he was locked in.
"That first time warming up, I was nervous for sure," Broadway said. "When I got in the game, they were gone and I was just [focusing on] pitching."
He repeatedly touched 97 mph on the radar gun at AT&T Park and finished the inning allowing one hit and no runs on 14 pitches, 10 of which were strikes.
"Pretty impressive," Brandon Belt said of Broadway's performance. "I had no expectations. I had never even seen him pitch before. I heard very little about him from the other guys. He came in throwing 96, 98 -- it was pretty cool. He kept the score [close]. He did a great job for us."
Parker, who started in right field, didn't fare as well in his first Major League appearance, going 0-for-3 with two strikeouts, but that is to be expected with a young hitter on a big stage.
"I'm sure he'd like to have had a hit today, but Parker's one of those guys who has been missing some playing time," Giants manager Bruce Bochy said after Saturday's game. "He's been working hard and ... he'll be back out there tomorrow."
Oliver Macklin is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.