You'd be wrong, then. The trend toward reduced crime started well before he became mayor.
Actually, I think the trend towards increased personal responsibility among minorities in NYC took a giant leap in ‘95 after the Million Man March. There was a change in attitude in many ways after that in a lot of people I saw.
But Giuliani knew what had to be done before that, and stuck to his plan in spite of the local liberal media crying and moaning about it.