You're Correct!

Golfers are always looking to increase distance in any way possible whether it be increasing arm speed or hip speed to attempting to produce more lag on the down swing by decreasing the wrist angle.

The lag angle built up between the wrists and the club shaft during the back swing should be approximately 90 degrees. This then needs to be maintained throughout the down swing whilst the hips and legs drive towards the ball until impact when the wrists will unhinge, release and deliver massive power into the shot using the momentum created from the bodys down swing movements.

A typically weak position with the wrists during the down swing is when they start to unhinge from the top of the back swing. This is called casting and it causes the angle of attack to become shallower but also reduces the speed which can be created through the impact zone.

The longer the wrist hinge is held on the down swing, the more powerful the release through impact will be. Be wary that you do not hold the hinge too long or the club face will struggle to square up to the target at impact causing shots to go right.

A good drill for this would be to turn your golf club upside down. Hold it from the hosel down on to the shaft, and swing normally. With your natural swing you will be able to hear a noise which would indicate the wrists unhinging. The location and noise of the hinge will help you work out where it occurs so you can work on making this noise louder and later in the swing for a better and more effectual down swing.

Hitting down on the ball will only increase the angle of attack. It will not necessarily make the lag between the wrists and the club shaft more hinged. To achieve the feeling of hitting down more on the ball, you will load a lot more weight on the left side and extend your arms towards the ground. This will not create more lag or power but potentially you may hit the ball fat or cause a driver to be skyed.

Loosening the grip can in fact cause more lag during the swing. This amount of lag will make it extremely difficult to unhinge through impact which would invariably leave the club face open at impact, and depending on the swing path, could slice the ball.

Tightening the grip will have an adverse effect on creating more lag because it will cause the wrists to remain rigid throughout the swing which will mean the angle of hinge between the club shaft and left arm will not reach 90 degrees and cause a loss of distance.

The grip pressure should be loose enough to reach 90 degrees and hold it there for the majority of the down swing until it is time to unhinge and release through impact.