Qualls said the biggest change playing for Houston is the Astros being in the American League. The Astros changed leagues last season.
Qualls worked as a setup man for closer Brad Lidge in 2005, when the Astros reached their only World Series. He went 6-4 that season with a 3.28 ERA.
"It's kind of cool," Qualls said of being an Astro again. "It brings back good memories. Houston drafted me out of college and called me up to give me my first chance in the Major Leagues. It's all good memories."
Qualls now occupies the locker of former Astros star Craig Biggio. He said he wasn't aware of that until he saw Biggio in the clubhouse a couple of days ago. "He said, 'You're in my locker,' " Qualls said Biggio told him. "I told him I'd take good care of it."
The struggles by the bullpen were a major part of Houston's league-worst 51-111 record last season.
"Honestly, I had no idea," Qualls said. "I wasn't keeping track. They were in the American League and I was in the National. I knew they weren't winning many games, but I didn't know why."
The Astros brought in Qualls, Matt Albers and Jesse Crain to strengthen this year's relief pitching.
The bullpen helped Houston beat the New York Yankees in two out of three games to open the season.
"We have good arms," Qualls said of the Houston 'pen. "We can definitely have a good year with that group of guys down there. The camaraderie is good. It's about picking each other up. It would be nice to bring that winning attitude back to Houston."
Qualls, 35, will need to be a leader of the Astros bullpen.
"It's something I've done in the past, being the older guy," he said. "I embrace that role and take pride in it."
Gene Duffey is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.