The short answer is yes. One of the biggest faults in beginner to intermediate golfers is sliding of the hips away from the target on the backswing. Maintaining a lot of flex in the right leg also limits one’s ability to turn the hips far enough away from the target line.
Sam Snead, Hogan and many other greats used the straightening of their right legs in the backswing to increase hip rotation and limit hip slide. Look at a few of the best ball strikers ever and see how they use their legs properly and powerfully. You will notice that unlike the casual golfer the trail hip is closer to the target at the top of the swing than at set up!
Most players average or worse golfers start with too much flex in their legs which gives the false sensation of power. Too much flex is difficult to overcome on the backswing. In a good leg work swing, the trail leg extends on the backswing, flexes to start the downswing and then extends quickly on the downswing. This helps create aground vertical force which is a big reason so many of the younger players hit it so long. The maximum of ground force measured by machines is when a player has their lead, left arm parallel to the ground in the downswing.
Next time you practice start with a very small amount of flex and then extend the right or trail leg on the backswing until its almost straight. For most of us, this feels very awkward and powerless. After you hit a bucket of balls you should start to see your results improve dramatically.
Jim Hartnett, PGA