Perdomo, 24, was in uniform for Friday's game against the Giants at PETCO Park. He spent Spring Training with San Francisco but was designated for assignment Saturday.
The Giants selected Perdomo in December's Rule 5 Draft from the Cardinals and envisioned him as a part of their bullpen mix. And for most of the spring, it appeared Perdomo would make the team.
Perdomo had a 3.48 ERA through his first 10 Cactus League appearances during the spring but faltered late and finished with a 6.75 ERA.
"He's a guy with a heavy sinker and a good slider," said Black, who noted Perdomo threw in the low 90s.
The Padres claimed Perdomo for $25,000 after the Washington Nationals and Seattle Mariners passed on him.
Perdomo has a career record of 11-11 with a 2.92 ERA in 129 career Minor League starts with only 103 hits allowed in 157 1/3 innings with 191 strikeouts.
To make room for Perdomo, the Padres optioned outfielder Drew Macias to Triple-A Portland. Macias was 0-for-2 in his only at-bats as a pinch-hitter.
That means the Padres will carry 13 pitchers for the foreseeable future, which could make for some creative decision-making late in games regarding pinch-hitters or double-switches.
Should the Padres decide they need another position player, outfielder Emil Brown, who is playing with Triple-A Portland, would seem to be the logical pick.
Then again, starting Friday, the Padres play 12 games over the next 13 days, so carrying one extra pitcher might make sense.
The Padres also announced Friday that they designated infielder Travis Denker, who was playing for Double-A San Antonio, for assignment.
Pitcher Wilton Lopez was claimed off waivers by the Houston Astros. Lopez pitched in the Padres organization the last two seasons.
With the moves Friday, the Padres currently have 40 players on their 40-man roster.