Much of the information in that piece is inaccurate or out of date.
Stoke's pitch was 100 x 64 metres several years ago (under Pulis) but has since been increased to the standard size of 105 x 68m. That is the size now required by Premier League rules (Rule K.15) unless the nature of the stadium makes it impossible to have a pitch of those dimensions.
The quoted size of Hull's apparently huge pitch (18% bigger than most!!) is in fact the area of the whole playing surface. Their pitch is the standard 105 x 68m.
http://kcomstadium.com/about-the-kcom-stadium
WHL is correctly stated at 6700 square metres (100 x 67m) and is the smallest in the PL. The new stadium will be 105 x 68m.