In a summer of highly-inflated transfer fees, value has become increasingly hard to determine.
On one hand, the Iliman Ndiaye is a player of superlative skill, evasive, quick and wonderfully entertaining with the ball at his feet.
Ndiaye was responsible for 73 of Everton's 250 completed dribbles last season, the highest share of any Premier League player.
Everton fans may also point to recent moves in the Premier League involving Manchester City, such as the sale of Savio to Tottenham for an initial £75m, as further evidence that the club should have demanded more for Ndiaye.
On the other hand, Everton are effectively quadrupling the initial £16m they paid Marseille to sign Ndiaye two years ago for a player whose underlying numbers, at this stage at least, are not truly elite.
In the Premier League last season, Ndiaye only ranked joint third at Everton alone for goal contributions (nine), with Beto (10) and Kiernan Dewsbury-Hall (12) providing more.
It is reasonable to assume that those numbers for Ndiaye will improve in a more attacking team at City but his general creativity is also middling as things stand.
He created 36 chances in total in the Premier League last season, ranking him only fourth at Everton. Toffees midfielder James Garner created 26 more. Jack Grealish, whose season ended in January because of injury, created eight more.
Grealish has effectively replaced Ndiaye at Everton following his loan move from Enzo Maresca's side.
Casting the net a little wider, 45 Premier League players have recorded more goal contributions than Ndiaye's 19 since he made his Everton debut two years ago.
As a 26-year-old set to be surrounded by better players, it would be no surprise should his numbers flourish at the Etihad.
But even in today's money, £65m for Ndiaye's current output may not be as questionable a deal as it sounds.
