Get used to his movement first. I recommend trying out a parkour wrecking ball course. This will help you learn how to throw yourself round obstacles, and make him more predictable.
Next. Ball is hard dive. You wanna be flanking round, and smashing through the back line a lot. The more time the healers are busy, the more time your team can smash through the rest of their team.
Once your rope is recovered, check your health bar, and predict the outcome of the fight. Enemy HP, who’s focusing you, and what CC (Crowd control. Stuns, hinders…) they got. If you don’t think you can get anymore value out of the engagement, then retreat, find health packs, wait for your shield cooldown to recover, and then go back in for more.
Another thing is the bowling ball technique. If your team are struggling to make ground, then grappling onto walls the same height will throw you forward, allowing you to smash through their front line, knocking everyone out the way.
Grapple up for vertical movement. Grapple low for speed. Holding space bar shortens the rope.
Smash down, and then shield immediately. The more enemies around you, the more shield you are granted. When you retreat, give your shield to alies who are still fighting, while you go get your health back.
Using ultimate. There is 2 ways. Use it in the air, then pile drive to gain control over a wider area. Pile drive then ult to make a smaller but more dead area. A good trick you can do, but it takes practice. Ult in the back line behind the enemies. Then follow up with the bowling ball, and smash them back into it.