What is the DLS method?

If overs are lost, both teams no longer had the same chance to score. DLS estimates remaining scoring resources and gives a revised target, usually a par score that updates as wickets fall.

A team batting second with 10 wickets and 10 overs left has more resources than a team with 2 wickets and 10 overs left. That is why a collapse can suddenly put you behind par even if the run rate looks fine.