Why do defenders cost less?

I’ve never understood why the most expensive defender in footballing history is half the price of the most expensive attacking player in the history? Are they not just as important?

 

Obviously a striker or attacking midfielder will score you loads of goals and grab all the attention, but I can’t see why they are not regarded more equally. The stark contrast between the most expensive footballer in the world being Gareth Bale for over €90 million and Rio Ferdinand the most expensive defender at €46 million after his 2002 transfer from Leeds to Manchester United (I believe the initial deal was around €29 million and rose to around €33 million with a clause in the contract regarding a certain amount of appearances in a season). It amazes me that the entire list of record transfers is all attacking players until Rio crops up, followed closely by Thiago Silva, now of PSG.

 

I know it’s a given that players who do not play in the same position can not be compared, but surely they can’t be regarded more important than the other? If you’ve got a front three of Messi, Ronaldo and Falcao and a back four containing Zat Knight, Ryan Shawcross, Alan Hutton and Paul Konchesky, you may well score a ton of goals, but you’re going to leak a serious amount of goals that could ultimately lead to the team’s downfall. I’m not sure if I’m looking for a reduction in the cost of attacking players or a rise in price for defenders, but I have always found the massive difference confusing. As a defensive player myself, it hurts to see Fernando Torres cost more than Thiago Silva, who I believe to be the best centre-back in the world. And I think we all know who we would rather have in our team at the moment, right?!