Yeah but that £45m meant less to us and was less (percentage-wise) above what we should have expected.
Put it this way:
Barton was a player who probably should have been fired. Was never going to play for the club again. And the club were dirt-poor. £5m for a player who was a net negative to keep around at the time is great business.
Ferran was, and to a degree still is, a high profile, high potential, international. He has 35 caps at the age of 22.
City are now so rich and profitable that Ferran's £45m transfer (which we've supposedly received very little of so far) made a smaller impact than Barton's £5m transfer. Ferran was considered to be sold at market value, and many were complaining we didn't get enough for the potential they saw in the player.
These aren't comparable, and I'm not even taking inflation into account. These deals were 15 years apart.