After allowing three runs in his first four games with the A's, the right-handed Otero has not yielded a run in 13 of his past 14 appearances, recording a miniscule 0.42 ERA over 21 2/3 innings.
Gradually, his role in the bullpen has shifted as a result -- in a good way. Otero, who pitched in 12 games for the Giants in his first taste of the big leagues last year, is no longer simply being used to eat up innings with the A's trailing, rather he's been trusted to hang onto leads.
Take Sunday, for example, when he replaced starter Tommy Milone with two outs and a runner on second base in the fifth inning, his team clinging to a 5-3 lead against the Indians. He needed just three pitches to force an inning-ending groundout from Ryan Raburn, before compiling four more outs while allowing just one hit.
"Otero's been a real unsung hero for us recently," said manager Bob Melvin. "To give us an inning and two-thirds when he's finishing out the fifth, pitching the sixth and one batter in the seventh, that's a pretty good outing for us.
"You look at his numbers right now and they're really indicative of the way he's pitched. Bridging that gap to 7-8-9, that's huge for us."
Said Otero: "This is the type of pitcher I feel like I am, just throwing strikes and getting ahead of hitters and then trying to put them away as quickly as possible. I'm just pitching my strengths."
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.