Thing about confidence in a team is that there is probably nearly always somebody struggling to find confidence or not playing as well as they could be. This is especially true in cricket where peoples form must be coming and going all the time and to get every single person playing at the top of thier game is more rare that common. If you're part of a team where confidence is on the up then it means you can be 'parented' along. 'Don't worry, keep going, we're all with you, we have confidence in you, things will get better' [of course that kind of faith only lasts so long, but it gives you breathing space to get your act together]. I think Ian Bell is a classic example of that. If that same person is in a team where confidence is a little more fragile, then you might begin to feel a bit more vulnerable, bit more exposed, don't feel the support quite as much and you may not come through the tough stuff.
In cricket, particularly with batting, you could argue that you're always on your own, and it's always down to you and nobody else, but if there a good vibes around with other people in the team doing well, it must help. Collective forces can get very powerful, as history shows us.
The other thing about Australia was Clarke's innings. Good player, but has struggled against Broad. Broad's had the upper hand for some time. When Clarke came out to bat England's tactics were so so obvious it was, well, obvious - Broad comes back after only one over from Tremlet [great for Tremlet's confidence that] to bowl the short stuff at Clarke and Clarke gets the upper hand and goes on to make a hundred. Good for confidence or what? And the rest of the team watch from the dressing room and think hay, that's really cool. Osmosis rules! It matters.
It's all well set up, that's for sure.