Haven't seen anything of Blind so I have two quick questions:
1) What's his best position?
2) How good could he potentially become in that position?
Having a squad player who can fill in in several different positions would be very useful provided he is actually good enough for any of those positions in the first place. If we're only signing him because he's versatile though then he really isn't what we need right now. That should be a bonus rather than the best thing about him.
1) It's not easy to tell but i have to say that his best position is holding midfielder. Even van Gaal has said, during the WC qualification round, that his true position is the #6 role but he already had enough options there.
He made his breakthrough last season playing as a holding midfielder. In fact De Boer's decision to take him from LB and give him a crucial role in Ajax's midfield is considered the tactical manoeuvre of the last season in the Eredivisie. Not only did Blind flourish but Ajax, who were struggling in the first half of the season, started winning game after game immediatly after Blind played in the midfield.
Tbf i didn't rate him as a LB. He was rather slow for that position and his crossing still needs improvement. What made his managers pick him was his intelligence on the pitch. He is very good at reading the game, his positioning is excellent and he is extremely good when it comes to defensive and offensive transition.
Moving him in the midfield highlighted another big strength in his game, his passing. With almost 70 passes p.g. he became the conductor of Ajax's midfield, helped his team control the tempo and dictate play.
When Ajax were defending De Boer often asked him to man mark the opposition play maker, especially when Ajax wanted to press high. His positioning and ability to cover the whole of the pitch made him perfect for the role and helped Ajax apply high pressure while retaining their cohesion. He often operated as a third CB because Ajax play with their full backs in advanced positions on the pitch.
Whenever Ajax had the ball he was the player who controlled the tempo and triggered his team's positional play. He watched all the off the ball movement from his central/deeper position and he could easily make the right pass. He also had no problems in one touch football and pass n' move style whenever Ajax needed to increase the tempo. He was involved in the build up play and almost every attacking move.
2) These are his two biggest strengths, his passing and his reading of the game and positioning. He looks like Busquets when defending and Alonso when attacking but at a lower level, right now. You could say he looks similar to Carrick, with the ability to cover more spaces and press more the player with the ball but without the key forward passes.
Judging from what Pep tries at Barca with Lahm at #6, i'd say this is what LvG has in mind for Blind, if we make a move for him. I don't know if Blind will ever reach that level or how long it will take him to get there, but if Louis believes he can i'm ok with it.