Better golfers generate the power in their swing from big body muscles. The club head gets accelerated into the ball via forces generated from a solid rotation.
Chris Lundell, Alta View member, showed me some videos from Joseph Mayo, director of instruction at TPC Summerlin. Chris' son Carson, who plays on the BYU golf team, recently took some lessons from Joe. These videos from Joe really highlight how to drive the hand path coming up and left through impact, which is what happens when you power the golf shot with the turn of the body.
So Chris was in practicing feeling the rotation and this was one of his really solid swings. He then went out to Alpine Country Club later in the day to play a round and told me
"Connected swings all day. Nothing coming from arms and wrists. Best ball striking in at least a year"