I think its about the way in which statistics are collated and then weighted against a basket of indicators -which would include more than titles or cups won, but things like continuous presence in the First Division/Premier League and so on; Arsenal has a better record than Liverpool for example; Arsenal relegated just once, Liverpool at least twice -and the stats I think I saw would have gone back to the 1870s. I don't know it is a fact.
I also wondered if Jock Stein had Jewish origins, but it turns out Stein is a derivative of Steven, there is an entertaining website on Jews here
http://www.jewornotjew.com/profile.jsp?ID=998
I think it can be slippery, had either Celtic or Rangers played in the First Division/Premier League their records would be poorer; Mexico always reach the World Cup finals because they play useless teams in the qualifying rounds.