FAULT: SWING PATH TOO SHALLOW
When the club falls below the correct plane on the downswing the club travel on a very shallow angle into impact. This can cause a poor contact that will be very low on the face of the club, hitting behind the ball, and ultimately a shot that is pushed off-line. This is more powerful than being too steep, but not as powerful as swinging the club on plane during the downswing.
FIX: TEACHING SHAFT
Notice the teaching shafts or even a clubshaft on the ground about 8″ behind the ball. This is there to require you to take the club away on a more vertical plan and also to swing on a downswing that is on a more vertical swing plane. If you still swing a that shallow plane you will hit the teaching sticks. After working with this aid for a few practice sessions you should notice that you will be taking more divots, ball launching higher, and shot more on-line towards the target.