3) John Stones (Everton to Man City) - £47.5m

How does one become the most second-most expensive defender in the world at the age of 22? It's a position that takes players years to master and stamp their authority over and yet here was a youngster from a club that had won zilch who suddenly became rich thanks to Manchester City's deep pockets.
Everton were smart enough to milk City for every penny when John Stones had a couple of impressive seasons between 2014 and 2016. The Toffees had earlier rejected as many as three bids from Chelsea; varying from £20m to £30m.
But when City offered to pay a record fee for an English defender, Everton gleefully accepted. Stones has since failed to really impress under Pep Guardiola, making a number of costly mistakes as City finished third.
However, he is still only 23 and has a number of years to learn his trade. Unfortunately, he price tag could weigh him down for the first few years.