I think balls are great for keeping your ham out trouble while you clean the cage. I've found that mine sometimes doesn't want to get out. She will willingly climb in but when I go to let her out she sticks her head out then goes back in and tries to run even though I am holding it
often though she will just jump back into her cage when she's had enough and nothing beats running around free. Even if they have a lovely big cage and wheel (as mine does) sometimes they just want to experience new smells and surroundings.