Back Off Your Bowling Ball Speed
If you are losing balance and control when delivering your ball, then back off your bowling ball speed.
Try to throw too hard is as much of a deterrent to good shotmaking as is throwing too slowly.
Controlling bowling ball speed for better spare shooting and for hitting the pocket consistently requires being in balance during your slide and release of the ball.
One technique is to warm up until you are a ready to deliver a ball during a practice session at your maximum speed. In other words, throw the ball as hard as you can without losing balance and without losing eye contact with your spot on the lane.
Once you can deliver the ball as hard as you can, back off to about 85% - 90% full power and deliver your ball a bit more slowly than your maximum speed.
If you bowl at about 90% speed, you will have an ability to control your shots, pick up routine spares consistently, make adjustments on the lane for changing lane conditions, and know when to change bowling balls.
Other players might use a 2 or 3 mph faster or slower speed than you but the same strategy applies.
Use the ball speed relative to your physical capabilities so you develop consistency and accuracy.
Avoid the tendency to try and heave the ball down the lane at the corner pin spare.
If you are not well practiced at using your maximum speed at spares, your chances of missing the spare increases. Avoid losing balance and control trying to throw too hard.
Consult with your personal coach/instructor or a local bowling pro shop professional to help you develop techniques to control your ball speed.
In order to use your spare shooting system effectively, you must be able to deliver the ball fast enough to react consistently but not so fast as to lose control or balance.
Practice as often as possible if you wish to improve your technique.