Brighton defender Shane Duffy has flourished since leaving Everton.
Shane Duffy of Republic of Ireland
This season has been something of a disaster for Everton so far, with Ronald Koeman paying the price having been sacked in October.
One of the major problems Koeman faced was a torrid defence, with Everton conceding 22 goals in just 11 Premier League games; only West Ham have leaked more goals at the back.
Even after landing England international Michael Keane over the summer, Everton continue to struggle at the back, and a huge part of the problem has been ageing duo Ashley Williams and Phil Jagielka, who appear to be in decline.

Their struggles therefore make the performances of Brighton star Shane Duffy all the more galling, given that Everton sold him to Blackburn Rovers in the summer of 2014.
Duffy, now 25, joined Everton from Foyle Harps in his native Ireland back in 2008, but made just 10 first team appearances before being offloaded to Blackburn for just £1.5million (Liverpool Echo).
Duffy moved on to Brighton in 2016 after two strong years with Blackburn, and he has been a key part of Chris Hughton’s tight defence this season, with only six teams conceding fewer goals than the newly-promoted Seagulls this season.
Republic of Ireland defender Shane Duffy celebrates after scoring against Denmark
The centre back has now grown into a talisman for club and country, as he also plays a key role for the Republic of Ireland, even scoring against Denmark on Tuesday night – and his performances this season have resulted in Everton fans taking to Twitter to suggest that the Toffees should look to re-sign him and pair him with Keane.
The problem with such a bid – if Everton do attempt to re-sign Duffy – is that they would have to pay a huge fee to land him again, possibly around 10 times the amount the Toffees sold him for just over three years ago.
Brighton are under no pressure to sell and wouldn’t want to lose an improving centre back who can still get even better – meaning a £15million asking price would be far from outrageous from Brighton’s perspective, especially after seeing Keane leave Burnley for Goodison Park in a huge deal over the summer, and Everton may just have to live with their mistake.
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