Virgil van Dijk (Liverpool)
Virgil van Dijk's £75 million move from Southampton to Liverpool was initially deemed to be an overpaid deal for a defender.
A year later, the Dutchman is on the receiving end of high praises from the same critics and rightly so. The Netherlands international has commanded the centre of defence at Anfield and has played a pivotal role in maintaining a defence that has only conceded 20 goals in the Premier League.
The Dutchman was recently named PFA Player of the Year to become the first defender since John Terry in 2005 to receive the award.
His consistent performances all season has led critics to believe he is in strong contention for this year's Ballon d'Or as well.
Honourable mention: Manchester City's Aymeric Laporte
Gerard Pique (Barcelona)
After a torrid start with Barcelona this campaign, Gerard Pique quickly made up for his deficits by establishing one of his best seasons in recent years.
The 32-year-old reminded the world why he is considered one of the best centre-backs in football with rock-solid performances at the heart of the Blaugrana defence alongside Clement Lenglet.
The Spaniard has helped the Catalan giants keep 20 clean sheets in all competitions this season and was a key player in the club's journey to a consecutive La Liga title.
Honourable mention: Ajax's Matthijs de Ligt