In all honesty, as good as he is at what he does, I think his skill set is something we don't need quite so much of
He can't play as the proper number 6 in a 433 because he can't pass the ball, which limits us to the 4231 we play now. Essentially we play the system we do because of him and Sigurdsson - they're both good at what they do, but they're both pushing 30, have obvious flaws, earn big money and restrict the way we play
If we could replace Gana with a player who can pass the ball properly, can sit as a number 6 and is maybe 75% as good at what Gana does as he is, we'd be better off for it IMO
£25m isn't enough, but £35m would be worth considering - we'll never make better money on him than we would right now and there isn't a bottomless pit of cash available, even if it's considerably greater than it used to be. Teams still need to consider trading profits and he's a prime candidate for it