"It's good to be up here," Otero said. "It's fun to be up and be a part of this team, we're obviously doing well. We had two tough losses the last two days, but it was good to get in there and get my feet wet with the new guys on the team. I'm feeling good."
Otero debuted in San Francisco last season and pitched in 12 games for the Giants in April and September before being omitted from the postseason roster. He said his approach has remained the same since working his way back to the big leagues.
"I'm still not trying to do too much, but the hitters are better up here obviously, so when you try to change who you are as a pitcher, usually it doesn't lead to success, so I'm just trying to stay who I am, pitch to contact, attack the zone and go from there," Otero said.
A's manager Bob Melvin said he's been pleased with what he's seen the past couple days from the newcomer, who's also on backpack duty for the bullpen. Traditionally, the least experienced reliever carries around a pink backpack -- Oakland's version includes a fuzzy white unicorn on the back -- that typically includes candy, nail cutters and other items.
"He's going to get his share of work and he has already to this point," Melvin said. "I don't think it was paramount that he had to have a clean inning yesterday. I think he's pretty confident with what he's done this year."
Andrew Owens is an associate reporter for MLB.com. Follow him on Twitter @OwensAndrew. This story was not subject to the approval of Major League Baseball or its clubs.