Smith allowed a one-out hit to Matt Szczur on Sunday, but he responded by striking out Dexter Fowler looking and getting Kris Bryant to line out to left to end the inning.
"It felt normal. I know it's been, what, six years? But it felt normal," Smith said with a chuckle.
Smith, a fourth-round Draft pick by the Red Sox in 2002 via UC Riverside, reached the Majors six years later with Boston in 2008 as a reliever. He pitched parts of three seasons in the Majors with the Red Sox and Brewers, going 1-0 with a 5.19 ERA in 50 relief appearances.
The Mariners released the righty in May 2011, and he didn't play again professionally until 2013, when he signed with the Wichita Wingnuts of the independent American Association league. He spent 2014 and 2015 at various stops within the Padres' organization, before finally signing with the A's this past offseason.
Smith wasn't sure what to expect then, but he knew Oakland provided a viable path to perhaps one day returning to the Majors.
"My mindset was just to finish strong," Smith said. "Maybe possibly get a job for next year. But going into the season, obviously with Oakland, anybody [at] any time has a shot. I wanted to keep doing what I was doing."
Smith went 6-8 with a 3.93 ERA in 22 starts with Triple-A Nashville, logging 130 2/3 innings. The A's are in need of durable arms and finally called on Smith, who learned the news Saturday from manager Steve Scarsone.
Despite not working as a reliever all season and facing the top of Chicago's order, Smith looked at ease. It was appreciated by A's manager Bob Melvin, who praised Smith after Oakland's loss.
"It's been a while since he's been here, too," Melvin said. "When you're not used to coming out of the bullpen, that can be unfamiliar territory as well. I thought he handled himself well."
If it was an emotional moment for the veteran, he concealed it well.
"[I was] probably a little emotional when they told me last night, and I contacted my wife and three daughters," Smith said. "When I got here it was not peaceful, but I enjoyed watching the game."