I think maybe when you are getting the link from Flickr you are selecting the 'default' size which is medium, 333x500 in the thread you linked to.
Try selecting the large option in the drop down menu (as long as it meets the size rules here) when getting the link and see if that makes any difference.
The stuff I put on here I usually ensure it is uploaded to Flickr in the correct size then there is no more resizing to be done that is out of my control.
Paul.
I tried the large, and TP resized it (still soft), I then tried Lrg Medium , still soft. Also it seems to bring the contrast down a bit, so it makes the overall image a bit grey.