It's a possibility that Neymar could be very successful at Barcelona but it's a risk and it comes at the cost of possibly alienating very talented youngsters that don't cost a penny(besides wages) like Tello, Deulofeu, and Cuenca. If we're going to take a risk on a young player who isn't that proven then why not just give Tello a lot more minutes next season and start giving Deulofeu some minutes instead of spending a bunch of money on a player who is easily bullied off the ball by Tim Cahill?
The number one priority should be a truly quality CB.