To some extent i think the win percentage stat is irrelevant anyway.Depends on what a manager inherits-if someone takes over a pile of steaming dog crap,then he isn't going to register a 50% win rate straight away,no matter how good he may be in the diverse aspects of management.So many variables to consider-resources,recent club history,player acceptance,director cluelessness,all can contribute to making a good manager look bad or vice versa.Most managers,outside of people like Ferguson,Wenger etc,tend to end up with chequered careers-i guess you only have to look at the records of people like Warnock,Holloway,Sturrock and Reid for confirmation-regarded as abject failures at some clubs,yet revered at others.