Here is a scan of a WJ that I lost in a burglary several years ago. Note the full borders all around, although there is light pink discoloration along the home to firstbase line:
To me, full borders are the best attribute, and less than 5 1/4 throughout would downgrade. As for grading, IMO fraying or severe staining would be the worst defect. These also suffer from poor registration, fading, product/other staining and centering.