4. Diego Forlan
The Uruguayan remains one of the great ‘what if’s’ of English football. Arriving from South America with a big reputation, the striker just couldn’t find the net with any sort of regularity and was quickly shipped out to Villarreal. However, once in Spain the floodgates opened, and he became one of the most prolific marksmen in Europe before being picked up by Atletico Madrid where he repeated the feat. An unsuccessful spells with Inter Milan began to herald the end and he is now seeing out his career in Japan.