Stauffer, 22, was 2-0 with a 2.33 ERA and 31 strikeouts in six starts with the Beavers. The second-year professional is coming off his best start with the Beavers after tossing 9.0 scoreless innings and allowing six hits and one walk in a no-decision against Salt Lake on May 5.
At the time of his promotion, the first of his career, Stauffer ranked sixth in the Pacific Coast League in ERA, also ranking among league leaders in innings pitched (38.2).
Stauffer was a first-round selection (fourth overall) of the Padres in the 2003 draft.
Also on Monday, the Padres purchased the contract of right-handed reliever Brian Falkenborg. In 13 relief appearances with Portland, Falkenborg, 27, was 3-1 with a 1.98 ERA.
Falkenborg, who signed with the Padres a minor league free agent in the off-season, has eight major league appearances to his credit, coming in stints with Baltimore in 1999 and the Los Angeles Dodgers in 2004. He is 1-0 with a 6.23 ERA (12er, 17.1ip) in his eight big league appearances.
The moves were necessitated when the Padres placed right-handed pitcher Tim Redding on the disabled list and designated left-handed pitcher Randy Williams for assignment.
Ironically, the Padres finally won a game when their fifth starter worked on May 3, although the problems at the back of the rotation only worsened during the week.
The Padres had been 0-13 in games when the No. 5 starter worked prior to defeating the Rockies 2-1 Tuesday at Petco Park. RHP Tim Redding allowed only one run on four hits over seven innings but did not get credit for the win.
But Redding was rocked and injured in his next start Sunday in St. Louis, and LHP Darrell May gave up four runs on seven hits and two walks in just 3 2/3 innings Friday while working in the spot normally manned by the injured Woody Williams.
Since the trade of No. 5 starter Ismael Valdez to Florida last July 31, the Padres are now 1-14 with a 8.43 ERA when the No. 5 starter has the ball.
The No. 5 starters themselves are 0-11.
Redding is 0-5 with a 8.76 ERA, although he may be headed to the disabled list if Sunday's departure were any indication. He was scheduled to return to San Diego on Monday for further exams.
As David Eckstein was singling to center on his second at-bat of the first inning, Redding went to the grass in front of the Busch Stadium mound clutching his right shoulder. Redding later walked off the field, but he was having difficulty raising his arm to shoulder level.
Earlier Sunday, he had said his shoulder was tight.
Stauffer could put a stranglehold on the number five spot in the rotation if he blossoms in his chance while Redding is on the disabled list.