I should let OP clarify because I only think I know the xHR stat .. but I believe it compares every ball hit to ballpark layouts. So in the Vaughn example ... he has 80 career HRs but if all of his batted balls were in MKE he would have 105 of them, etc. This is kind of an interesting little find. I would love to be the nerd (respectfully) that the Brewers hired to simply spend their day perusing the BS site to find the guys who would perform much better in MKE vs their current divisions.
Also, the BaseballSavant page is dangerous. You can go down some gnarly rabbit holes. For example, Cal Raleigh has 41 home runs this year but he has hit 51 baseballs that would have been a home run in at least 1 park.