Get a 2nd ball. Make the one you're holding the 'better' one to have. Wave it, shake it, tease him with it. When he drops the one he had, toss your's. Pick up the one he dropped and repeat. You're teaching him that if he drops it, he'll always get it back...no need to run away with it.
This is the same technique that's used for resource guarding.
This is the same technique that's used for resource guarding.
