Trudeau isn’t even the weakest current PM in the Commonwealth. Anthony Eden would be May’s main competition over the past century while Neville Chamberlain got hit hardest with hindsight. Check a lot of ‘bad PM boxes’.
Australia’s revolving doors of PMs this decade has also been incredibly weak. Seven different PMs Since 2010 makes it tough to leave your mark on the domestic stage never mind the international stage. It’s an office that isn’t leading anything with regards to policy.