Hughes could probably have won Premier League with City if he had been given enough time and money. There isn't much to separate him and Mancini in my opinion. Both are mediocre managers. Hughes got them to play brilliant football for a while with Ireland and Robinho, Mancini got them to play brilliant football for a while with Agüero and Silva. The money is behind most of their achievements, character flaws in managers and players are behind most of their shortcomings.