San Diego manager Bud Black said Wednesday that Street -- who is back in San Diego -- is still walking with a limp.
"This is going to be past the 15 days," Black said.
Street was injured when he ran from the mound toward first base on the final play of the Padres victory over the Pirates, which ended on a ground ball to first baseman Yonder Alonso.
Street was diagnosed with a strained left calf after the game and then officially landed on the disabled list the following day.
He then returned to San Diego on his own as the team finished its series in Pittsburgh before starting a series in Atlanta against the Braves on Monday.
Dale Thayer, who replaced Street earlier this season, earned his sixth save in Monday's 4-1 victory over the Braves. Thayer converted all five of his save opportunities when Street was previously on the disabled list with a strained right lat muscle.
There's no timetable as to when Street will return, though it won't likely come before September.