1. Erik Lamela (Tottenham)
The Argentine attacker arrived in London in the summer with a huge reputation developed from putting in sublime performance on a consistent basis in the Serie A. The £30m club record signing was supposed to be the replacement for Gareth Bale, but he hardly ever got to grips with the playing style of the Premier League. 9 appearances and 1 assist later, he was quietly shipped out to his former club Roma on loan in January, and may not return next season at all, proving to be the biggest flop since Liverpool signed Andy Carroll for £36m in January 2011.
(Stats via Squawka)