As far as flights go, that normally helps, but could mean nothing too.
Let's look at the AA system.
American is #2 at DEN(behind UA/UA Express), and they have a fair number of flights. However, where do those flights go? DFW,MIA,ORD,LAX,STL and other AA hubs/focus cities. So basically, DEN is not a place to make an AA connection.
Now, take SJC(or RDU if you want). Good AA focus city. In the eyes of some, it is a mini-hub, but I consider it a focus city. There are a lot of flights to secondary markets and they even have an NRT flight. At one time, they had TPE and CDG complementing NRT. But those flights are history. Now, there are still a fair number of AA flights that are not to hubs or focus cities and the fact that you have Eagle operating there(?) brings connecting pax. Still, it doesn't have the amount of flights that I would consider to be a true hub.
Now, bring BOS, and JFK. Those are midsized hubs. Too many flights to too many destinations to warrant them as focus cities, but for whatever reason, AA does not consider those airports as major hubs.
Now, the true hubs. DFW,MIA,SJU, and ORD. AA has many banks and in most cases has a monopoly, or a healthy share of the percentage of flights(as is at MIA and DFW). ORD is special because you have United competing side by side with American, but at the same time, both have large operations to many cities and in Chicago's case, it is AA's European gateway. Now, DFW. AA is well known for having a monopoly at DFW. They have 11 banks with around 54 flights each and have a wide variety of destinations. MIA, AA's Latin American gateway with many flights to Latin America which bring lots of connecting pax continuing onto other US points and possibly Canada or Europe. With San Juan, SJU serves as AA's Caribbean/Bahamas/US Virgin Island gateway which brings a bit American Eagle operation in. Pretty much at true hubs for a major airline, you will see flights going all over the world. A great example of this is United's Chicago hub or American's DFW hub. Also, airlines tend to make their terminals at hub airports a little bit nicer.
Give me a break, I created this username when I was a kid...