Question I have is what is he trying to accomplish/correct/compensate with the shaft being mounted at the back?
There has to be a reason for this set up, Yes/No?
There was an article on golf.com today about Tony's change to this putter. It's to help him not miss left. I'm not really adept at linking articles but this is the article:
golf.com/gear/putters/tony-finau-piretti-putter-custom-mayakoba/