Whoever actually threw the Thor ball, it was Jack who took it and ran with it.

It's always seemed to me that the Fourth World was Jack, given free reign to do the things he'd WANTED to do in Thor, but didn't feel like he had the freedom (or that was getting paid enough to provide his Coolest Ideas).

While the Fourth World remains my favorite moment in comics history, honestly, it's been the target of so much scrutiny that I don't really have anything left to say after this.