The Bundesliga's 15th-placed side came from behind twice to beat Bayer, who sit second, and Streich believes that his team deserved their luck because of their "passionate display".
"We're used to conceding early this season, so seeing Leverkusen take the lead three and a half minutes in wasn't a shock," he told Bundesliga.com. "However, we were the luckier of the two sides today.
"We competed on an even footing with Leverkusen thanks to a passionate display. We gave it our all. We wouldn't have been able to put in such a performance at the end of last year, yet we still have a long way to go."
Freiburg are now three points away from the bottom two.