A good ditching does always have an element of luck doesn't it? The fact that they all are alive is a great thing and the Cpt has obviously done a great job getting the aircraft on the water in one piece. The odds were significantly stacked against him. Night, poor wx, significant swell, maybe aircraft type too.
Luck???? Depends on the pilots skill and experience. If these are sadly lacking, then yes, luck plays a big part.
I would have thought that a Westwind fuselage would probably be the best one could have for ditching. I mean to say there is just a fairly round and smooth single hull to put onto the water. It is not impaired by, wings, engines, undercarriage. To me it would be the (near) perfect platform to conduct a "water landing".