I would never use the balls for several reasons.
>>the vent holes are known to trap toes and feet causing injury
>> temperatures in the balls can reach fatality levels in a short time
>>something like going down a flight of stairs can cause injury or traumatic scare events.
>>Hamsters rely much on smells when they forage and explore, they don't have that in balls.
A running wheel of appropriate size and some run around room in their cage is all a hamster needs.
Give them some out of cage time, socializing, or a fun playground for them gives them a sense of freedom.
All mammals need enrichment in their lives or become bored and depressed. Give your hammie a play area with chew toys, things to explore, hides, familiar things fro its home, stress free, safe from falls.Escape proof.
A large bin works, something like a bathtub you can join your hamster and just let it do its thing, don't forget treats, they are highly food motivated.