As a technical player he was relatively limited, as a leader of men with the ability to drag his team through a game on sheer determination there have been few like him. Ultimately that mental intensity and exceptionally high standards he demands out everyone around him has hindered him to some extent, not at man u (though it did get him the boot out of there in the end) but more playing for Ireland (the Saipan incident before world cup 02 being case in point) and its also held him back in his management career as he can't seem to be able to work well with players now who aren't as good as he and who he played with were.