4. Knee Flex
The last critical angle is knee flex. The bend at the knees is more important than you might think. The key is to realize that the knee flex you establish at address should be retained during the course of the backswing and into a portion of the forwardswing.
The desired amount of knee bend should again favor slight over drastic. The reason for this is simple: The greater the amount of knee bend at address, the more the knees will have to unflex to create a posted left leg at impact. The move from deep to tall is tough even for the most coordinated of players. Similarly tough is the task of holding a deep knee flex throughout the downswing. From a deep-knee bend start, most golfers will wildly move the knees. Contrast this scenario to what you see on TV. Today's great players employ simple knee and hip movements so it becomes much easier to return to impact consistently.
Don't fall into the trap that says strong leg and knee action in the swing creates power and leverage. Sure, we use the lower body, but only to assist our upper body to deliver the clubhead into the back of the golf ball on the proper path. In my opinion, standing taller is better, and learning how to coordinate a taller body is a much simpler task than one that is bent, cramped and flexed at address.