Alvarez will eventually be a Barcelona player. Atlético Madrid is in a sticky situation now: they don't want to sell to Barcelona, and they don't want to keep the player either. Still, the player only wants to go to Barcelona, so at the end of the day, Atlético Madrid has two options: either keep an unhappy player or sell to Barcelona for the price Barcelona is willing to pay. It's a lose-lose situation for Atlético Madrid