potentially dumb question

So I oppose stop and frisk on basic racial equality and civil liberties grounds — the policy looks like a straightforward excuse to harass poor people of color — and believe that we should end the War on Drugs immediately, etc. I also recognize that every such interaction, in the world we live in, amounts to an opportunity for police violence against black men. So I’m very glad that Bill de Blasio’s directive has resulted in a major reduction in the amount of these behaviors.

But I’m a little confused by the argument, such as here from Amy Davidson, that crime has still been falling despite the number of stop and frisk incidents being reduced from almost 700,000 in 2011 to less than 50,000 this year, so therefore the practice doesn’t reduce crime anyway. Stop and frisk is a policy intended to ferret out crimes. Like I said, I don’t agree with that policy. But when you massively reduce a practice that is specifically designed to look for crimes — and increase the number of reported crimes for statistics — aren’t you inevitably going to have a lower crime rate in that case? You’re reducing the number of times cops are checking people for crimes by 650,000. Of course the crime rate’s going to go down. Right? Or is there something that I’m missing? I could be guilty of just bad reasoning here, and again I strongly oppose stop and frisk, but I’m curious.