#2 Kevin de Bruyne
After starting his professional career with K.R.C. Genk, Kevin De Bruyne was one of the most coveted young prospects in Europe when Chelsea landed him in the winter transfer window of the 2011-12 season on the deadline day.
After spending the remainder of the season at Genk, he was loaned to Werder Bremen where he excelled and was voted as the Bundesliga Young Player of the year for the 2012-13 season.
The midfielder was widely expected to stake claim for a spot in Chelsea's squad at the beginning of the 2013-14 season but he featured only three times. The Belgian even started the first league game against Hull City, which marked Jose Mourinho's return as Chelsea's manager.
Soon after, he fell out of favour and departed the same season in January after securing a move to VfL Wolfsburg
De Bruyne's spell with Wolfsburg catapulted him into one of the best young attackers on the continent and he won the Bundesliga Player of the year for the season 2014-15. Chelsea's league rivals Manchester City then secured him in a £47 million pound deal (reported) during the 2015-16 season.
Now, 27-year-old, the Belgian has shown exactly why Chelsea were wrong in selling him as he now features among the best midfielders in the world. Currently, in his fourth season at Manchester City, he is an integral part of his side, managed by Pep Guardiola who broke every record as they marched to a historic Premier League title win.
During his second spell in England, he has scored 22 goals and registered 43 assists in the league.
A midfielder boasting of an excellent technique with a passing range second to none and providing a consistent goal threat will be a welcome addition any football team on this planet.
A current look at Chelsea's attacking options other than Eden Hazard would puzzle anyone as to how the Londoners let this mercurial talent leave.