"He needs to pitch," Black said.
Street finally did pitch on Friday in Washington, tossing a 1-2-3 eighth inning in the Padres' 8-5 loss.
Street hadn't pitched since June 26, meaning he hadn't appeared in a game in eight days while missing each of the first seven games on this 10-game road trip.
So what's Street been doing? For one, working in the bullpen with pitching coach Darren Balsley and bullpen coach Willie Blair on a few mechanical things.
"He's feeling better about his slider," Black said. "[Specifically] the spin on his slider and also where his elbow is. There's been a little variance there, he's been under the ball."
Street is 0-4 with a 4.45 ERA and 15 saves in 29 games this season and has allowed 10 home runs in just 28 1/3 innings.
As for not pitching in a long stretch of games, Street didn't seem too concerned.
"It's going to be like that sometimes," he said. "Sometimes, it's going to be feast or famine."
Black said Street was going to pitch in Thursday's 8-2 loss to the Red Sox, though knowing that shortstop Everth Cabrera was returning -- and a pitcher would be optioned -- the team decided to use rookie Burch Smith, who threw 2 1/3 innings. Smith was optioned to Triple-A Tucson on Friday.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.