Stop-and-frisk under Bloomberg was a failed policy by any conceivable metric. Crime in every major category continued to plummet even as the number of stop-and-frisks was drastically reduced, rendering the logic Bloomberg used to justify the policy during his tenure 100% wrong 
Bloomberg suddenly deciding to "apologize" for this as he prepares a presidential run has to break some kind of record in terms of transparently craven political calculations
He presumably wants to run based on his record in NYC, and now finally concedes that his signature "public safety" initiative in NYC was a gross misuse of power and a systematic violation of civil liberties. Mind-blowing to anyone who followed this issue at the time
