I went and had a look as I remember length of contracts being discussed around the time Fabregas signed an eight year contract with us.
If anyone remembers ex-Wigan player Andy Webster, you might remember his dispute with previous team Hearts resulted in a new law whereby players can unilaterally cancel their contracts without just cause three years after they signed it (two years for those over 28), though compensation would be payable. It's been used a couple of times, most notably by Jonas Gutierrez to move to Newcastle, but not much since. I imagine increased player power means there is little need to use the rule to move, that most unhappy players simply only need to make themselves difficult long enough for the club to agree their departure.
But what I find interesting is the existence of that rule probably means eight year contracts must be pretty much unenforceable for clubs, assuming a player has suitors willing to stump up whatever any compensation may amount to. Longer contracts probably inflate the compensation owed, so on a separate note I wonder if that would even then in theory become an issue challenged by players in future. But on point, if these long contracts are unenforceable I do wonder why they are allowable as largely only serve to financially benefit clubs for FFP purposes. It's clear that's the motive in any case.
There will no doubt be exception cases where there is a lack of suitor clubs willing to pay compensation for a player and an extended contract must stand as the player cannot afford to pay up himself, but if we're talking the top end of the game where FFP is predominantly targeted, I can't imagine that would happen much.
I suppose it also raises the question of what a suitable contract length is. Why is eight year not suitable but four or five are? We all know why eight isn't suitable, but why would five be acceptable for example? I imagine certain clubs will push back hard on this.
