When you're player down, the defense will typically run a backer. There are usually six defenders on the outside in a shell, with one defender following and backing the ball. The backer can pressure out onto the ball and help teammates.
The goal of the player-down offense is to occupy the backer and create an even opportunity on the backside.
Instead of trying to dodge through both your defender and the backer, engage the defense and make them commit.
A good setup is to put a player in the middle and create a 2-man game where the backer is.