If you look closely at that photo, the result is really weird. The black pieces behind the plane of focus have very uncertain positions that the software didn't bother fixing. It's bokeh, in a way. A horrible way.
You're right, that's like no lens blur I've ever seen.
It's a lot like an unsharp-mask halo though
Right. Also surprising how much fine noise there is in the background — it ‘should be’ out of focus enough there there would be nearly no noise at all…
I think that's just a zoomed up picture with low depth of field. I'm not a photographer so correct me if I'm wrong. The chess pieces in the background look still quite big compared to the pieces in the front. It suggests that the photo was taken from around 30-40 cm.