Bowed vs Flat Lead Wrist @ Top of Swing

How can the lead wrist help your game?

First, you have to know how flexion and extension affect the position of the clubface. 

Flexion: This is the bowing of the lead wrist. Bowing will close the clubface. If your clubface tends to be open at impact, getting the wrist in a more bowed position will help square up the clubface. 

Extension: This is the cupping of the lead wrist. Cupping will open the clubface. If your clubface tends to be closed at impact, getting the wrist in a more cupped position will help square up the clubface.  

Second, It will change the plane of the downswing. We won't get into how flexion and extension affect the shaft plan on the downswing. 

Third, understanding how the lead wrist affects your ball flight will ultimately help you gain more consistency with your direction control. Here is a good key to hold on to. The more stable you make your lead wrist, the more consistently you will be able to control your clubface.