You've highlighted his strengths in the defensive side of the game but he does also have some big weaknesses. His positioning when we are being countered is continually suspect, he leaves gaps in the defensive line and is slow to recognize the danger and get back in position. His defending of balls in the air, whether from crosses or from long balls has also been a weakness.
Yes, sometimes he does recover well and make up the ground to get the last ditch tackle in but he also puts himself into those situations where he has to put in that last gasp tackle as well. He's good, but he's not perfect and he's not so good that we couldn't bring someone in who is better. He has the potential to be one of the best, but he doesn't want to reach that potential with us. So what's the harm in letting him go for a big profit and wisely reinvesting into someone who wants to be here long-term.
You say it isn't a Rom situation and I say it is worse. Rom has been talking himself up for a move for the last 18 months but Stones actually went ahead and put in the transfer request. There's no debating what that means. I don't know how you have convinced yourself he will give us another year since the lad has not come out and clarified his position since that transfer request was rejected. Even if he did want to stay another year I would have to ask what benefit there is to us in that, is another year going to increase his value which is inflated with the potential premium or is it more likely that he half-arses it and with a wider set of performances to analyse in a team experiencing transition that his value depreciates instead?
What is the point in us giving him a year to iron out his mistakes that will cost us points when it isn't going to lead to us selling him for more, and selling him is inevitable? I honestly can't see a case for it other than some misguided sentimentalism that isn't reciprocated from the player.