Who's to Blame?

Did Richard Cohen really blame the police for the hundreds of Middle Eastern refugees who sexually assaulted German women on New Year's Eve in Cologne?

Here's what he wrote:

The Cologne incident, too, while larger in scope, has not — or not yet — been repeated. There, too, the police have learned from their mistakes.

What, pray tell, were the police's mistakes (note the plural Cohen uses)? Not racially profiling MIddle Eastern migrants? Presuming that refugees would tend to be law abiding? Allowing migrants to assemble in large groups? Downplaying the incident initially so as not to draw attention to it?

It''s a pity Cohen doesn't elaborate on this important point.