This year, Yabu sports a 2-2 record with a 1.95 ERA in 18 appearances. In May, the 6-foot-1 right-hander has allowed just two runs on six hits in 12 innings of work.
Not bad for a non-roster invitee.
"I'm just focusing on keeping the ball low. Definitely location is the most important thing for me," Yabu said through a translator. "I change the way I pitch depending on the hitter. Depending on who's up, I decide which pitch is best for that situation."
Yabu said he can throw up to six different pitches in any given inning, including a fastball, cutter, slider, changeup, split and curveball. During his first season in the Majors, Yabu wasn't able to analyze hitters as much as he currently does because he didn't know about all the technology that was available to him.
Now that he does, Yabu said he analyzes hitters more than anybody, which is probably why he's so dominant no matter who's up. Left-handed hitters are batting just .242 this season off Yabu, and righties have fared even worse, hitting at a .162 clip.
Earlier this season, manager Bruce Bochy mostly used Yabu as a mop-up reliever. But if the Japan native keeps performing the way he has, he could see a more prominent role in his future.
"He's been huge for us," Bochy said. "He's given us a lot of quality innings, and I've used him as a long-relief guy, a setup man. He knows what he's doing out there, and on every team, you have to have a guy you know you can give the ball to and he'll give you a quality outing."
Yabu doesn't know what his future in the big leagues holds, but he knows he loves playing in the United States.
"If I do good this year, I may be able to play next year," Yabu said. "Baseball here, there's more speed, more power, and it's more fun to watch. This is the highest level of baseball, and this is where I want to be."