Yes, expensive, but so was Dani Alves in 2008 (33 million)He is quality, probably among top 4 LB in the world after Marcelo, Alaba and Filipe Luis but he is so expensive.
Question is rather, can he be one of the best in the world in his position for the next 7-8 years.
Haven't seen much or noticed much of him even when he is playing, which is probably a good thing for a defender.