Didnt Arteta not cut it at a club before coming to us?
Didnt Pienaar fail at his club?
Coutinho didnt make it at Inter either. Some of the best players moved clubs and were poor, Shevchenko, Veron, Torres, Kaka to name a few.
Sometimes a player just fits a club, hopefully thats the case with him and us. He did say that at Milan he had 6 managers in 4 years, all with different methods and styles which made it hard to get any consistency, especially as a young player so maybe a settled team will do him the world of good.
Plus im sure Walsh/Koeman will have researched his personality and spoke to people who have played/worked with him and if they are happy enough to bring him in, then we should give him a chance.