Deco has indeed played for Barcelona and Chelsea, but morally Deco is closer to Barcelona. According to news circulating, Deco has tried to convince Leeds to release Raphinha to Barcelona even though his offer is lower than Chelsea. Raphinha has personally asked Deco to stop his transfer to Chelsea and prioritize Barcelona. Raphinha really wants to play For Barcelona, he can immediately blend into the Barcelona-style tiki-taka game, for that reason he wants to be part of the Barcelona squad even though the salary he gets is lower than what Chelsea is offering.
I think the decision is now at Leeds United whether they want to accept Barcelona's proposal for Raphinha or they prefer and agree to Chelsea's said higher proposal. I might agree that Raphinha could join Xavi's squad in Laliga, but of course Leeds will prioritize which proposal benefits them more financially.
Raphinha is a striker who might deserve to be at the Camp Nou under Xavi, he will definitely develop with the schemes and strategies that Xavi applies to his team. I'm sure about it, but now we just have to wait how that decision is made. If Raphinha manages to be at Camp Nou, Barcelona's strength is believed to be much better.