The interesting part of Chelsea's long contract strategy is that while it is risky when it comes to poor performers, if the market continues to heat up those salaries probably won't look as bad in three or four years' time. In theory, it means locking in promising young players to those wages for the peak of their careers. But you need most of them to perform or you're screwed long term. The best you can hope for is a small loan fee to offset those big transfer fees.
But what kills me about Chelsea is their continuing strategy of using the academy as a sales cash cow when it could be such a cost effective way to build their squad long term. They could have had Mount, Rice, Tomori, Guehi, Musiala, Abraham, Lamptey and Livramento in the squad alongside James, Colwill, Broja and Gallagher. Instead, they've sold them off early and got in vastly more expensive players who've performed worse while letting the two best players in that group slip through their fingers before reaching senior level. At least when Man City do it, they buy well at the top end.