Too stubborn for his own good. Its not about signing bruisers but having players that can give you a number of different options. They have a good defensive midfielder in Song, but they need another centre back (not rugged, as Vermaelen is good at that), maybe some wingers like Adam Johnson who can give width and get crosses in and a striker who can lead the line with some presence, like Adebayor.
Plus they have to be able to mix it. Trying to play football one way is too easy for teams like Man Utd, who will absorb that and beat you in different ways. Playing one style and having wingers who are practically the same will get them nowhere.
They have a good squad. Vermaelen, Song, Wilshere and Van Persie is a good spine, but they need to pad it out with options, rather than loads of players like Rosicky, Denilson.