Leeds have now taken 10 points from their last five matches, with wins over Wolves, Reading and Birmingham followed by a draw at Hull and Saturday’s defeat to keep them on 58 points.
The result came after Evans made three changes to the team that drew 2-2 against Hull last weekend.
Whelan told BBC Radio Leeds that his former club are not helped by the uncertainty surrounding the manager’s position.
He explained: “This isn’t a great Charlton side – they’re down and done but Leeds weren’t good enough.