This can get complicated if you don’t pay attention, so we will keep it simple.
I will use euros and the conversion from pounds is a guesstimation from the time of the transfer, but these are the key points to his contract and what it means for Arsenal should FCB decide to sell.
Length: 5 years, 7m€ per year.
Initial Fee: 35m€ paid in two parts. 6m€ loyalty fee due to transfer waived by Cesc.
Add Ons: 6m€ for 1 CL or 2 La Liga titles in 3 years, was later reported to be broken down per La Liga title.
Clauses: 30m€ First Option, Right of First Refusal clause. This is the one most people don’t get. FCB have to either get a bid in and accept and no matter that offer, say it is 40m€, we have a right of first refusal to buy him back for 30m€.
Or if FCB decide to sell, we have a right of first refusal for the 30m€.
We do NOT have an option where we can go in blindly, pony up 30m€ and FCB HAVE to sell to us, this is where people are getting confused.
In the contract there is also a 50% Sell On clause, meaning, if there is a bid for him and we pass on buying him with our first option clause, we get 50% of the transfer fee.
Edit – We would get 50% of what is left over above the 35m€ base fee FCB paid for him. So if a 40m€ is accepted and we pass on re-signing him, we get 50% of 5m€.
The third scenario is that Cesc can convince FCB that he wants a move back to AFC and a mutual break of the above contract could lead to a transfer.
His release clause is unclear, there are reports it was 90m€ and others reported that it was 200m€.
What is not in dispute are the clauses above, the thing with AFC fan base these days is that they’ll believe anything that’s fed them as long as it fits what they want, and most want Cesc back, so there you go. Even the Daily Mail article eludes to these clauses and the need of FCB wanting to sell for it to come into effect, but everyone ignored that.
Hope this helps.