The left fielder homered and walked twice in three plate appearances in Saturday's 8-6 victory over the Padres, taking Tyson Ross deep on a fastball on the second pitch he saw this spring.
Asked if he'd shortened his swing, Bay said he's just finally regained the feeling he had at the plate earlier in his career before his struggles began.
"I don't think I've shortened it. I've kind of re-found it," Bay said. "I struggled for a while and it was more of trying to find something. I tried a million things, just trying to save face, and nothing was working. I got so far away from doing what I'd done before that I forgot how to do it.
"So, the last part of last year and all offseason and the week I've been here, it's trying to get my rhythm back to what I've always done. So what may appear a little bit different from the last couple years is probably what it looked like three, four years ago. It's kind of engraining that again."
Bay said the last thing on his mind was going deep in his spring debut, but "to get results, instant feedback, that speaks volumes at any level."
Manager Eric Wedge has taken notice of the three-time All-Star, who is one of several veterans the Mariners brought in hoping to add some punch to the middle of their order.
"He's looked good with every aspect of his game," Wedge said. "He's a proven veteran. He's just had some issues with injuries the last couple years, but he's healthy now. He looks good, he's in great shape, he's short to the ball with some pop. So it's nice to see him get off on the right track."
Bay said being healthy this spring has allowed him to "hit the ground running." And he said he's comfortable in his new situation.
"I've transitioned to a few different clubhouses and teams, and this so far has been the easiest one," he said. "Maybe it's because I'm comfortable with where I'm at as a player in my career. Being close to home is nice, but it's not the No. 1 reason. Maybe it's just the change in scenery and really just kind of integrating here and coming in with a lot of young guys and Raul [Ibanez] and Mike [Morse]. It feels like we've played together awhile and it's been really seamless."
As for his chances of making the Mariners, he appears to be in a battle with Ibanez and Casper Wells for the final outfield berths, but says he's not concerned with that at the moment.
"I'm more worried about what I can do," Bay said. "I understand there's a limited number of people and limited number of spots. I'm not so concerned about who does what. I'm worried about me. I was under that impression when I came here. It was, 'Hey, I still need to make the team,' no question. And that falls on me.
"I actually kind of like that, not falling victim to a number's game or something like that. If I make this team, it's because I deserve it. That's on me."