7. Bongani Khumalo
Nigel French/EMPICS SportBongani Khumalo was signed as a 23 year old (literally a couple of days before he turned 24) from South African outfit Supersport United in January 2011 - although this was off the back of a decent performance at the 2010 World Cup (during which he scored against France - his only international goal to this day), he was untested in a decent domestic league. You would think that Spurs would have learned their lesson, after having signed fellow South African international Mbulelo Mabizela from the same league a few years prior. Mabizela arrived at Spurs in 2003, just before his 23rd birthday. And the reason behind the purchase? He played well against Spurs in a pre-season friendly for Orlando Pirates, inspiring the South African side to a 2-1 victory. However, all things considered, he just wasn't very good. He made seven league appearances for Spurs, scoring one (admittedly incredible) goal, but he soon moved to Valerenga in Norway - where he failed to impress again - before moving back home. The weirdness of Khumalo's signing for Spurs is epitomised by the fact that he is still on the books to this day (he's now 27), but has yet to make a competitive first team appearance. Loan spells at Preston North End, Reading and PAOK in Greece were unimpressive, but he seems to have found his level at Doncaster Rovers, where he ended last season on his fourth loan spell as they were relegated to League One.