The flavor is very good and it keeps well which that with size all implys years of breeding. There are many possibilities and as you know many new varities were bred within a short distance such as staymans Winesap apple, Douglas pear etc. And who knows perhaps it’s a left over of the once popular fruit breeding programs in the area. See this article for info on staymans apple Stayman (apple) - Wikipedia. See this research on Douglas pear Douglas Pear. Google search
A. H. Griesa Experimental Grounds which was a well known nursery in the area in late 1800s early 1900s that did a lot of fruit breeding and research. Though they are best known for the Douglas pear they experimented with lots of different plants.