The Catalan club aren't willing to subsidise the player's wages
If Griezmann signs for Atlético de Madrid, Barça won't contribute a single euro towards his wage. Last summer, Barça let Luis Suárez go for a low transfer fee and agreed to subsidise some of his wages for the last year of his contract at Camp Nou, allowing 'Los Colchoneros' to offer him a higher salary.
If Griezmann were to sign for Atlético, the player would need to forget about his huge salary at Barça and negotiate a separate deal with his new club. Griezmann's main priority is to feel happy, and it is understood that he would be willing to accept a lower wage in order to return to his previous club where he was a fan's favourite.
As reported by SPORT, the club is looking at possible swap deals between the two clubs. Atlético are looking to find a new club for Saúl, since he is no longer a key player at the Wanda Metropolitano and Diego Simeone doesn't consider him to be a guaranteed starter. He wouldn't be a perfect fit for Barça, but it could be the only way to get Griezmann off their wage bill. The two players do not hold the same value, of course, and Barça is reluctant to lose money on a player who could still command a high transfer fee in the market. As such, they will ask for 20 million euros in addition to Saúl for the French international.