The opportunity to bring him to Belfast arose when Ulster's deal with Xavier Rush, who was to leave the Cardiff Blues for Ulster, fell through.
But the impact that Wannenburg has had since arriving in Belfast well and truly illustrates that every cloud has a silver lining.
Wannenburg has remained a very important part of the squad in his second season in Belfast, although injuries picked up both away to Edinburgh in January and at home to the same opposition in March have led him to miss a handful of games.
Ulster's director of rugby David Humphreys said: "While we're announcing now that Pedrie will be leaving us come the end of the season, it does seem premature to be wishing him, his wife Evette and baby daughter Isabelle well at this stage as I know he remains absolutely committed to our cause as we enter the 'business end' of the season."
Ulster Rugby will finalise the make-up of their squad for the 2012/13 season in the coming weeks.