He was never promising defender, but he was promising all around player. His defending was never great, and he was making mistakes when he came here, but he had some other amazing attributes like running through the midfield with the ball, having nice ball control, decent passing, great recovery pace and what not. Now he is nothing like he used to be, he is actually better defender nowadays but still makes some awful mistakes, but he is nowhere near skillfull with the ball as he used to be. I have no idea why some people still think of him as ball playing defender when he is nothing like that, he is actually very panicking with the ball, and most of his passes are backpasses to the keeper. Injuries obviously didn't help, it's actually surprising that he can still make decent run of form with his season being disrupted with so many injuries.
Anyway, I have no idea why is he still here. I wasn't against selling Blind, but surely you would rather keep him who is at least available all the time ahead of Jones who is unreliable as it gets, no matter how good he can play in around 7 games per season.