Many players do not use their non-playing arm properly. Often the problem is that you can sort of get away with not using the non-playing arm in many drills – either static ones, where you aren’t moving (i.e. working on basics with beginners), and often in moving drills where you know where the ball is going and so don’t have to make sudden unexpected changes in direction. And so players will sometimes get lazy and let their non-playing arm just hang there like a dead snake. (I call it “dead snake syndrome.”)
Often the consequences of a limp non-playing arm aren’t apparent as they affect your ability to recover from a shot – meaning it doesn’t so much affect the shot you are doing as much as it does the next shot. And then, rather than blaming the slow recovery on the lack of balance and fixing the problem, they call out, “I’m too slow!”
There are really three things about the non-playing arm you should focus on.