Making his first Major League start, Aumont buried the Phillies quickly in Friday's 12-4 loss at Citizens Bank Park. He allowed five hits, six runs, two home runs, walked seven, threw one wild pitch and threw behind one batter in four innings. He struck out three.
He threw 104 pitches, just 56 for strikes.
"I don't give up," Aumont said. "I'll keep working. I know I can do it. I've done it plenty of times."
Aumont joined the Phillies in December 2009 as part of the Cliff Lee trade with Seattle. The Phillies moved him from the bullpen to the rotation the following spring, but after struggling as a starter in the Minors, he returned to the bullpen.
He remained there, pitching sparingly in relief for the Phillies from 2012-14, but constant struggles with his command put him on thin ice entering Spring Training this year. He cleared waivers in March, and the Phillies outrighted him to Triple-A Lehigh Valley. A short time later, Aumont returned to the rotation.
He enjoyed some success early, but his struggles throwing strikes returned. He walked 25 batters in 26 innings in his last five starts before the Phillies called him up to replace Cole Hamels, who missed Friday's start because of tightness in his right hamstring.
Yadier Molina and Kolten Wong each hit two-run home runs against Aumont in the second, when he walked two batters. He walked two more in a scoreless third and two more in the fourth, when he allowed two more runs.
"It's more so mentally," Aumont said about his struggles. "It's just mentally, blockage. You start getting in those situations, and you start nitpicking a little bit. Not doubting, but ... it has to be between the ears. I've done it plenty of times physically. It's frustrating to just be in that position, fighting it.
"It was just a constant battle a little bit with myself. That's what it's been my whole career. Just me, myself and I out there battling. Nobody else. Because when I execute my pitches I get these guys out down there and up here. Just keep your chest high and keep working at it. The mental part is a big part of the game, and you've got to be strong at it."
Right-hander Justin De Fratus replaced Aumont in the fifth. He allowed eight hits and six runs in two innings. He threw 58 pitches.
The Phillies' bullpen has pitched 20 1/3 innings in the last four games.
"That's a challenge, keeping the bullpen intact," Phillies manager Ryne Sandberg said.