Blanks entered the game as a pinch-hitter for Yoenis Cespedes in the ninth inning, knocking a single before being caught up in an inning-ending double play.
Getting his first shot late in the game as Oakland had a huge lead, Blanks got started on the right foot.
"No doubt about it, makes you feel like part of it, part of the team right away when you're able to get in and contribute," A's manager Bob Melvin said of Blanks' debut.
Leading up to the trade, Blanks knew he might be moved.
"There were a few days prior to this happening, actually a friend of mine texted me and asked if I was traded," Blanks said. "I'm not really a social media person, don't really get online and look up a bunch of stuff. But lo and behold, a few days later, I'm trying to take a nap and I get a call that brings me here.
"But it's definitely all for the better, definitely a great opportunity."
Blanks appeared in five games for San Diego this season, going 2-for-10 and making a pair of starts at first base, his natural position. He figures to give Oakland an option at first base that can hit left-handed pitching.
"Well, we were probably a little left-handed-heavy at first," Melvin said. "[Blanks is] a guy that can play first and the outfield, has got some power, runs pretty well for a big guy and is versatile."
Blanks walked into a live clubhouse Friday afternoon, where half the team was huddled around a clubhouse TV watching a game of Tecmo Bowl.
"It's definitely a loose, good, fun place to be, and that's the appearance it has, and so far, it's definitely easy to come into that," Blanks said. "It's not like I came from somewhere that was like a dungeon or this and that, but you don't know that to expect.
"When you walk into it and get a sense of the air moving around, how people interact, it allows you step back and say: 'I'm where I want to be.'"
Wearing No. 88, Blanks took batting practice with the final group of Oakland hitters Friday.