Nematode, if you have not read this before, this link has some studies linked here that you can find and read about flavor.
http://ucanr.edu/sites/nm/files/76647.pdf
Sadly a K deficient plant that results in blotch ripening, greywall, or yellow shoulder is a serious issue. I have found that any fruit that has set will be affected, they have to go through a complete cycle after the nutrient deficiency has been corrected.
Good luck