Looks like Reihan Salam nailed it:
The deBlasio administration arrives in office, changes things cosmetically (here with a new, friendlier commissioner) and now stop and frisk is no longer an issue. Now, note that nowhere does it explain where this decrease comes from. Typical of all the poorly-researched reporting on the issue, no one mentions that stop and frisk numbers come only from filed reports. Maybe we’re going back to Bratton’s heyday of the early ’90s and stops are simply no longer being recorded. Maybe officers simply aren’t pushing as hard. Maybe they’re being more polite.
Absent actual shoe leather reporting, why would anyone take this claim at face value.