What is being offered by Chelsea that is so terrible that players are preferring to move to Barcelona instead of Chelsea? Or are the players just moving to Barcelona because they think Barcelona have a better chance of winning La Liga compared to Chelsea winning the English Premier League?
I think the second one is more likely, I doubt with their current financial crisis Barcelona could offer better salary or benefit than Chelsea. The competition in La Liga is not as tight as in Premiere League, the only Real Competition Barcelona got for La Liga is from Real Madrid, compared to Chelsea that they need to compete with Liverpool, Man City, Tottenham, and maybe Arsenal, Man Utd and Leicester too. This also mean that Barcelona will be almost definitely got the Champions League, while Chelsea has possibility to not joining Champions League.