Transfer fees don’t mean a great deal, the important thing was getting him off the wage bill. Transfer fees into the club and out of the club are amortised. The club cares less about things like that than the wage burden.
So comparing it to Man United, they have a 25 million sum but they have a player that will a) be hard to sell on elsewhere because if Chelsea couldn’t agree personal terms with the guy what chance anyone else and b) the burden on their wage bill will have no small impact on their ability to buy.
Will they be able to go back in for Mbeumo and pay Brentford the money they want?