FU Paladins have an Armor of +5/+7, FU Tatar Heavy Cav Archers have an Armor of +6/+7. Why are they still so bad?

They should at least feel tanky but they still melt to everything and I have a hard time using them :(

I rather use mangudai or kipchak. Cause the armor just feels like paper anyway for cav archers.