No, they haven't all been signed by Roman Abramovich at one time or another. The correct answer is they all wore Puma football boots in the late 1970's, and to prove the point, here are a couple of ads showing the first two on the list doing just that.
"Puma make fourteen different soccer boots. One of them will help you play better" said the ads. Had you taken the plunge and bought two, however, you'd have really seen your overall standard improve...
