Yes they work but I am not sure that it will be any easier on your shoulder.Do they work? My right shoulder is starting to object, I am not really looking for any of the automated gizmos, just something that will go a bit further then my pathetic efforts...
do you use one ?
Bumpers with a rope are much easier to throw than a ball. Much less effort needed with the rope and weight.
Also, I assume you have a left arm?
Toss bumpers every day left handed and you will quickly get used to it.