"He looked shell shocked," Green said later of the outing.
On Sunday, a very different Perdomo stepped on the mound for the Padres against the Reds. Making his fifth start after a plethora of injuries to the San Diego rotation, Perdomo pitched six solid innings, allowing three runs and striking out five. Although he came out on the losing end of a 3-0 game, Perdomo recorded his second career quality start.
"He's a long way from that right now," Green said. "He knows he can get big league hitters out. That confidence he has will carry him forward in the future and will give us an opportunity to evaluate him as we go into next year."
Perdomo was a Rule 5 pick by the Rockies and then traded to the Padres. While he had high upside, the 23-year-old righty had never appeared above Single-A before this season. The plan for the Padres was to deal with his struggles and then let him develop in the minors after this season.
While his numbers haven't shown it, posting an 8.49 ERA, Green believes that Perdomo has a good chance to make the Padres' rotation next season.
"He's got every opportunity to start here next year," Green said. "He's got a lot of time between now and then where we get to make a decision on who he is for next year. He continues to make strides."
Perdomo has been able to find success with a sinker that he's throwing more as the season progresses. And while his numbers don't look great, three of his last four starts have gone at least 5 2/3 innings and he's allowed three earned runs in all three.
"It's definitely been my best weapon," Perdomo said via translator David Longley. "I think it comes from a lot of work in the bullpen and a lot of work in the game. It's allowed me to get a lot of ground balls."
The biggest change for Perdomo, though, is in his confidence. He said that his confidence has increased 80 or 85 percent since joining the rotation on a regular basis.
"It's definitely helped me a lot," Perdomo said. "First and foremost, it's been an experience, it's helped me in terms of experience. It's given me a chance to work on all my pitches, sinker, slider and changeup. It's definitely been a big help, good experience."
Cody Pace is a reporter for MLB.com based in Cincinnati.