Spangenberg was in the starting lineup on Monday, making his Major League debut at third base in the series opener against Arizona. Campos and Erlin will be available in the bullpen for Monday's game as well.
To make room for Campos and Spangenberg on the 40-man roster, the Padres transferred outfielder Carlos Quentin and infielder Yonder Alonso to the 60-day disabled list. Alonso had surgery on his right wrist on Friday, and Quentin has a bone bruise on his left knee.
Campos began the season with El Paso but struggled in 11 games with the Chihuahuas, posting a 11.70 ERA over 10 innings. After a demotion to San Antonio, however, Campos improved and struck out 95 batters against 38 walks in 31 games to go with a 5.60 ERA.
"Campos has got a big arm," Padres manager Bud Black said. "He came on the scene last year with a good year in Double-A in relief. He went to Triple-A and struggled a bit out of the gate, so the organization took a step back and moved him back to Double-A. At the suggestion of our Minor League evaluators, we put him in a starting role to build his innings and get him some repetition, which I think worked."
Erlin returns from a sore left elbow that put him on the DL in May. He pitched in nine games -- eight starts -- for the Padres prior to the injury and had a 3-4 record and 4.53 ERA. Erlin will be available in the bullpen in the near-term, but may be used a starter before the end of the season.
Black also indicated that pitchers Frank Garces and Joe Wieland, the Padres' No. 18 prospect, will join the Padres, as soon as Tuesday. Garces is currently with San Antonio while Wieland pitched Sunday for El Paso.
Tim Powers is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.