• The wrong club length (again usually too long) takes a golfer out of an athletic posture - one that can give the golfer the best chance to make a good swing at the golf ball and create the mos distance and accuracy; and
• The wrong club length can make it more difficult for a golfer to hit the center of the clubface - and center contact is a key to creating the most distance for a given swing speed.

When I fit golfers for clubs, one of the first measurements I make is of the golfer's Wrist To Floor (WTF) distance.  I have the golfer stand in a comfortable position and measure the distance from the floor to the major lifeline in his left hand (for right-handed golfers).  Tom Wishon (Tom Wishon Golf) gave me permission to reproduce the chart below, which I look at after I measure Wrist To Floor for a golfer:

So for example, if your WTF is 36 inches, this chart suggests a starting best length for your driver is 44 inches.  This is not set in stone - there are many things that can affect what would be your best driver length - such as your swing tempo, your downswing release location, and your swing path.

Tom Wishon wrote an extensive article on Fitting Club Length in August 2009.  One of the most interesting parts of that article is his statement that if you have a outside to inside swing path you should not be playing with golf clubs that are longer than those suggested by WTF measurements.

What if YOU measure your WTF and find that your clubs seem to long for you?  Well, perhaps you can do your own test - hit some shots where you grip your club down to an appropriate length (sometimes this could be as much as 2 inches), and see what your results are.  If you find that you are making more center contact, getting more distance, and you feel that you are making better swings - well, you might be on to something!