"Well anybody can pull the ball". This often said phrase may just be the most incorrect statement related to hitting. While any hitter can hit the ball to their pull side, only few can do it correctly and with power. Often times the hitter is either trained and forced to hit the ball backside or don't release the barrel well enough to pull it effectively.
The Direction Drill uses constraints to force the hitter to stay through the path of the ball instead of rolling their hands and pulling the bat through the zone instead of turning it.
Evaluating the success of this drill is pretty simple. If you hit the noodle in the swing, you're doing it wrong. Don't have to pick up the noodle after every swing, keep going you're getting better.