msejnoha: I also suggested that it would be nice to have a meter in inventory that showed how much life was left in those odd half used balls. Whomever responded agreed that was a good idea and said it was passed along to the dev team.
LMFAO! The old "We tell the design team" saying...
Also, a showcase of "competence" - this meter has been existing for a year(?) now - it shows on single balls in the inventory.
But, it doesn't help when you lose that last ball OOB or in water. Then, you should have some more balls in your bag, or the buy-in-game feature should work. I rely on it, too, and have not been disappointed yet.
Mind you that you may visit the Pro Shop through the game, to buy&add THAT SINGLE TYPE of balls to your bag.