So, some context.
Villa offered a decent fee for Gallagher, which Chelsea accepted. Gallagher declined to go there, which is his right of course. Gallagher then declined a new contract offer. So now we have a situation where Gallagher's contract runs out in 12 months, he has rejected a new contract, and declined to go the club that tried to buy him.
Atletico Madrid then enter the picture with a reasonable offer for Gallagher, which he accepts, and Chelsea accept. There is just one problem. Atletico have La Liga PSR issues and they have to sell before they can buy Gallagher. Chelsea know they have to sell to Atletico or risk losing him for free in a year, because Gallagher doesn't appear interested in the other interested clubs - Spurs, Villa, Newcastle, Everton.
So that's how we've found ourselves in a situation where we're picking a random Atletico player to buy to ensure we don't lose Gallagher for free.
The entire mess started with Chelsea's insistence on selling Gallagher. The contract offer I mentioned earlier, that he rejected? Yeah that was a shit 2 year deal that nobody in their right mind would accept, especially considering Chelsea are handing out 7 year contract to anybody that does as much as breathe near a football pitch. So it's a mess entirely of Chelsea's own doing.