Exactly, those 73k likes are liking your facebook page, not your site (URL). Test using your facebook page in OSE, how many facebook likes does it show? I am guessing about 73k
It has nothing to do with "where" the like took place, visiting your site, the user can click the LIKE button within your facebook page plugin and they are liking your facebook page, not your Website.
No one knows how or even IF social interactions help rankings, we are all guessing they do, but no one is certainly sure or knows how much they help. That said, a like to your URL is more valuable SEOwise, however, people liking your URL just liked your URL, while if they like your facebook page, you can have constant contact to those users.
You decide whether to have the like button or the like box, both, or a like button with your facebook page as the href. I would actually go with the like box or the like button using my facebook page, that way I can earn users that I can actually reach later.