If you cant clear the ball then 90% of the time you are wasting effort hitting it, it will either be set up for the enemy or it will go nowhere and you will be out of position to defend the goal. The current goalie will always have a good shot at clearing the ball, but doing so requires someone to take his position. Brawling for the ball is a gamble that sometimes works if you pinch the ball, but otherwise it will be a slow clear, the enemies will take positions for defence before it gets to their goal, this is in a scenario where they didnt have a guy ready to center the slow ball again.
Most of the time challenging the ball is not worth it, instead predicting where enemies will put it and positioning yourself so that you can use that information gets you a long way.
edit: Hitting the angle on the wall isnt hard to do and with decent force it will send the ball past the middle line. Super easy to follow up and is hard for the enemis to benefit from if they are positioned well.
Finally getting better at the aeirals, getting 80-90% on the allstar training consistently. Does pay off a lot in pubs..