How much did United write off with Falcao's loan?
You win some you lose some with transfers. A player's value to one club might not be the same as to another club.
Anybody can look at some great signings like Kompany and Zab for very low fees, but that's not typical. People can equally look at Torres for 50m, or Carroll for 35m, but these aren't typical either. It's cherry picking bargain successes and pricey flops. We've no idea what Sterling will or won't be, but City obviously feel the odds are he's going to be great. We could be wrong. That's life. We could be right too.
United are having to spend heavily, and they have their own set of gambles to take. Chelsea bought Cuadrado and Costa, one worked out well, the other didn't. It's nothing new.