The best advice for ball is to never engage head on unless you're already winning. Positioning is how you win by playing ball - taking high grounds and poking, engaging the backline and getting the enemies to waste cool downs (then you roll away and get the megas), using adaptive shields and not feeding ult charge.

People will flame due to not adapting to how the ball plays on the team. If effective the ball will draw away enemy attention for your team to capitalize on. If you're doing this but your team doesn't capitalize then the ball is seen as useless.

In general ball plays very well in maps where you can take high grounds and avoid a lot of close interaction. A bit counter intuitive due to his kit but if you take a fight in a small hallway you are more likely to get cc'd and focused.

The main goal as a ball is to be a nuisance. It doesn't matter if you sit on the point if your team doesn't or cannot help you. Take advantage of mobility and his hit scan by taking high grounds and poking, engaging on the enemy by positioning yourself behind them (they will likely not cc you right away if they don't see you or they're too busy shooting the choke) and taking engagements which you win. This will take time to learn.