2. Mario Balotelli
Brought in as a replacement of sorts for the outgoing Luis Suárez, Balotelli simply never lived up to the hype.
His €20 million price tag wasn't astronomical, but at the age of 23 and after a strong spell with AC Milan, he was viewed as a talent on the rise.
Unfortunately, he scored just once in 16 Premier League appearances for Liverpool, and was loaned back to Milan before too long.
Amazingly, Balotelli's struggles followed him back to Italy where he scored one goal in 20 league appearances for Milan after his return.
He's put up some good numbers in France and Turkey in the years since, but never really returned to the biggest stages of football, and certainly did not become the talisman for the Italian national team that many hoped and imagined he might.