You can have both of the following situations at the same time, but I am going to separate them for it to be easier to understand and the video will help as well.
An active cast is when the right hand grabs the club and throws it at the ball, losing all angle and the power and energy the rotation of the body creates. It doesn’t take advantage of centrifugal force unwinding the hands and squaring the club.
A passive cast is where the backswing is so long, there isn’t enough strength or body rotation to get the club back to the ball, so the club essentially just drop on the ball through force of gravity. People need to understand (as I said in the “full turn” post and video) that having a short swing is OK…actually, it’s often better. JB Holmes has one of the shortest swings in golf and is one of the longest hitters in golf.
You must start simple and build from there. The simple answer for the active cast is to maintain a nice medium grip pressure (equal in both hands) and take some of the control from the hands and give it to the turn.
The simple answer to begin solving the passive cast is to shorten the swing till you reach a point your body can accelerate the club all the way through impact.