Wan Bissaka had one PL season in a bottom half club. He went for £50m. He was the same age as Spence is now, who has played more than twice the number of matches.
I don't think Spence is an amazing talent, but I do think he is comparable to WB in terms of ability and potential.
I don't expect a ridiculous fee for Spence either, but this view the fee will be £10-15m is numb.
The only player Middlesbrough have sold for many years at a ridiculously low fee was Patrick Bamford to Leeds, as has been proven.
I think Gibson knows that Spence can bankroll most of a promotion push. £20m will be the minimum he will settle for.
Add the Derby donation and that is a very good start. A lot can be funded with £23m.