Chelsea's pursuit of John Stones last summer was comfortably the most well-documented transfer saga of the window.
The Blues had three bids rejected for the Everton defender, the highest of which believed to be around £38 million, and ultimately failed to lure one of Europe's hottest prospects.
However, whilst Stones is regarded as one of the best young centre-backs in world football, his recent form suggests he's not yet ready to make the step up.
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Recent reports have seen the England international linked with not only another possible approach from Chelsea, but bids from Spanish giants Real Madrid and Barcelona. The fee being thrown around is £50 million - an amount that would make him the most expensive defender of all time.
His age and potential has played a large part in his valuation, yet recent showings would suggest that perhaps he's not worth such a fee.
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For all his composure on the ball and reading of the game, it's easy to forget Stones is part of one of the leakiest defences in the Premier League, with 34 goals conceded so far.
Against Swansea last weekend, the 21-year-old was responsible for the first goal his side conceded, his lazy back pass allowing Andre Ayew to nip in before being taken out by Tim Howard. This isn't the first times Stones has gotten himself into trouble at the back.
Since arriving at Everton, Roberto Martinez has tried to introduce a keep-ball style of football at the club - but it hasn't always paid off. There's a time and place to play beautiful football at the back, but it seems the Spaniard is yet to enforce this simple defensive rule.
Defensively, Stones has looked questionable too in recent times. For Swansea's second goal last Sunday, the youngster didn't get tight enough to Ayew and and saw the Ghanaian's goal-bound shot deflect off his leg and in.
During the Toffees' Capital One Cup semi final second leg against Manchester City on Wednesday, he was the wrong side of Sergio Aguero when the Argentine headed home from Kevin De Bruyne's cross.
Europe's elite sides expect their defenders to be comfortable on the ball and able to play out from the back, which Stones is perfectly capable of, but his defensive frailties suggest that a move from Everton would be untimely.
The centre-back has great potential, but he's not yet ready to make the jump.