Migration to the European Union via the Western Balkans Route has been slowing for some time. Determining the precise factors leading to this decline is complex. It may be that weather and the progressive closing of border crossings along the migratory route north, are contributory factors.
According to the UN High Commission for Refugees, the figure for average daily arrivals of refugees in Greece for March 2016 was 870. That figure had declined to 134 per day by mid-April.
The core intention of the EU-Turkey agreement which emerged from the March European Council is to break the business model of the people smugglers who are profiting from the suffering of the vulnerable. Critically, it should stop people getting into unsafe boats and risking their lives.