In relation to Jon's voice, I spoke to my dad about it who is a classically trained singer (was a choirboy who performed in bands when he was younger). I showed him the Brisbane 2013 performance. He said that Jon's voice was clearly very damaged given how reasonable it was in early 2013, it's certainly not just him being tired. He did also say that Jon sounds better now than he did then, as well as 2016/17 which I found interesting.