When a player is sold, the club receives a fee but then has to pay the remainder of the players contract or an agreed figure of compensation.
Thats definately not always the case, usually just the original signing on bonus is the case if the club is pushing the player out.
Alonso/Arbeloa would have had their contracts paid up
If a player gets £2m signing on fee to be spread over 4 years and we decide to sell them after two, then they can quite rightly claim that they are owed the remaining £1m and it is that what gets paid
I'm not Rafa's biggest fan but what you said is incorrect