I get you. In terms of the one player in isolation its awkward. What was he on, 5m a year? So worst case is an unwanted player, taking a space costing 10m over two years. Getting 8m instead is damn useful.
I know most chelsea fans wont want to actively discuss it, but managing to sell 3-4 unwanted players within the space of a few days to the same league, should at least be raising some eyebrows rather than (nothing to see here or coming up with every excuse or reason). TBF, I think you specifically have.
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Im not saying its illegal, because its clearly not. But its very very helpful. In fact if they had paid you 30m for Ziyech ,it would certainly raise bigger questions (but who is to determine the price other than the buyer / seller much like when we paid an eyebrow raising 80m for Antony or Maguire)
Theres an element of all factors aligning here, player wanting to move and being comfy (their religion might help, but the money / wages will certainly help), the club(chelsea) needing them gone ASAP and the league (Saudi) wanting higher profile players.
I wouldnt complain if United managed to shift about 5-6 players to the saudi league, or wherever we can get buyers to improve the budget on offer. However if we randomly sold players in the next week to the Qatar league, and then were taken over by Qatar, it would certainly be questionable for me.