Here is a description of a drill that helps a bowler with improving their timing as well as freeing-up the swing. This drill can be done on the lanes, at home or in the gym. Most importantly, the drill works.
SLOWINSKI PUSH DRILL
(click right for the full article Slowinski Pushaway Drill, Bowling Talk, Malaysian Today, October 20, 2006)
The bowler will only take the first two steps of a 5-step approach in this drill and maintain this position through two swings.....
(1) DRILL SET-UP = Have the bowler set-up in the stance. Specifically, have the bowler place the ball in front of the shoulder, elbow at their side with the non-ballside hand supporting the bowling ball. I ask the bowler to only have the slide foot 1 inch (2.5 cm) in front of the ball-side foot at the start. This will automatically create a shorter first step. They should have slight knee bend and slight bend at the waist.
(2) Take a normal first step with the non-ball-side foot
(3) On the second step, they are pushing the ball out-and-down to achieve the elbow-knee-heel intersection. They do not take another step as the ball swings freely. At this point, the ball-side foot is used for balance.... you want them to feel this firm push position....
(4) When the ball returns, from the first swing, they load it back to it's orginal position for 1 quick moment (i.e., ball in front of the shoulder elbow at the side balance arm hand for support under the ball). The feet remain with the ball-side foot still forward and firm for good leverage.
(5) They push out-and down and swing freely again.
(6) Think Step --> Push --> Swing --> Pause and Load ---> Swing --> Stop --> dry the hand ---> repeat
I have used this at the gym with a medicine ball that has a handle as well. But, a bowler can train with this at-home as well. As I say, if you do this drill for ten minutes each day, you will be shocked at the amount of progress you will make with your swing. As a coach, this will help you help your bowlers free the swing and improve the timing.
NOTE # 1: I teach this as a 5-step set-up drill. I believe strongly that it is easier for bowlers to learn with 5-steps since the body is in motion prior to moving the ball.
NOTE # 2: Step-push = I teach the making an effort to intersect the elbow-knee-heel on the second step. This allows a bowler to easily change ball height in the stance while maintain a smooth timing feeling.