I think the internet proves there is often smoke without fire!
Over the months after a signing there are 'leaks' of salary. How accurate they are I don't know. These figures you mention could just be an average of what is rumoured.
It seems strange that the yearly salaries quoted are made up from round-ish weekly figures. Wouldn't a contract be made up as a round-ish yearly figure? I'd have thought agents would be asking for £Xm per year or £XXm over a long contract, not asking for a weekly wage. For some reason, the media love 'per week' figures and you can bet they are rounded up, and then some.
Also, the figures quoted may include bonuses based on a good deal of success; something that hasn't happened for a while! The media always state DB9 cost us £24m and yet I remember it as £17m or so plus add-ons, many of which we are unlikely to have to pay. Still, £24m sounds a lot more spectacular than (for example) £19.18m!