That performance dropped Mahay's ERA to 2.13 in 35 games and 42 1/3 innings. He's flourishing as he alternates with right-hander Ramon Ramirez in setup situations for closer Joakim Soria.
The "May Day" call to the bullpen often goes to Mahay.
When he's warming up, the 37-year-old pays special attention to an attribute he's cultivated over the seasons -- maintaining balance.
"Tempo in the game is huge for me," he said. "If I have a slower tempo, I stay balanced all the way through the zone.
"I don't fall off to the third-base side. Once I do that, my fastball will stay up and away, my offspeed pitches will stay up high in the zone and there won't be much action to them."
If Mahay stays balanced, pitches directly at the hitter and avoids the fall-off, his pitches stay lower with downward movement.
"That's what works for me," he said. "Some pitchers can throw and fall off to the base side and still be successful. But if I do that too often, I'm not going to be at my best when it's time to make a pitch."
So far, he's been at his best more often than not.
"Ronnie against right-handers and left-handers has been very valuable for us," Hillman said. "The biggest assets are changing speeds and throwing strikes, and also reading swings and throwing that split out of the zone because it looks just like the fastball."
Mahay has defied the odds, holding right-handed batters to a .219 average compared to .254 by lefties.
Except for the second half of last season with Atlanta, he's not been used regularly as a left-handed specialist. He did the job, though, holding lefties to a .189 average last season.
Mahay's fastball generally runs between 89-93 mph.
"If I get out of control and just go crazy, I can get it up there 94, 95, but I just don't know where it's going to go," he said.