I don't know the details, but from what's in that link, it was not just simply a landing in the wrong runway. Key points:
- The plane was cleared to land on 27R
- Apparently (given the NTSB recommendations shown there) it was a sidestep approach, meaning that the plane was supposed to do an instrument approach to 27L and, when in visual contact with the runway, make a side step to 27R.
- The airplane descended in fog busting the approach minimums of 600ft (that is a high minimum for a regular instrument approach, but not for a sidestep approach).
- The airplane touched down with the left main gear on the grass and the right one on the runway's shoulder.
- One of the NTSB recommendation was to publish separate approach plates for sidestep approaches.
- The tower warned the flight three times about the closed runway (according to a link in the wikipedia article).
(Note, the NTSB must have been an invited party in the investigation for being US the country of the operator, of the manufacturer and of registration of the airplane)