It is sort of odd that Flynn's reputation isn't bigger and more impressive than it is. Personally, I think that's about to change.
In my opinion, William Flynn's career inventory is probably more solid than any in history who did more than a course or two. Flynn's career inventory is actually smaller than I would have thought when you think of all the great courses he did but it seems to be only about 40 in number (although quite far afield). So far I haven't heard of a single dog that Flynn did--I don't think there ever was one.
But plenty is known about Flynn and he did quite a lot of writing about his thoughts and philosophies about many things to do with golf architeture--much of it in the USGA Green section reports. Flynn was fascinated by agronomy and very good at that aspect. And he had some very strong and probably radical ideas about golf and its architecture and clearly some opinions that many on this website would probably resist!
It is also important to understand William Flynn, the man, to start to understand his thinking about golf architecture and his career. Flynn was clearly sort of a daredevil in his personal life and he was clearly a man who knew very well how to ply important connections in his career. One can see a very definite connection or thread of powerful people in golf and in industry and society in almost all of Flynn's contacts and clients and courses. Apparently all these contacts and clients liked Flynn personally and hung out with him drinking and socializing. These were some of the most influential people in golf and those central to the great courses of the time like Juan Trippe (Shinnecock) and Clarence Geist (developer of all of Boca Raton and very powerful around Philadephia). Indian Creek as well!
The so-called "Philadelphia School of Architecture" was far more a collection of architectural friends and collaborators than it was a particular design style and Flynn was very central in that "School", although he was younger than the rest and the last true vestige of it.
Toomey and Flynn also seemed to be a bit of a training ground and architectural clearing house with some of the assistants and apprentices he had like Dick Wilson, Red Lawrence and William Gordon.
But Flynn clearly had his own ideas about golf architecture and he clearly stated he intended to make some changes from what he termed the "obsolete ideas" of the old school! Flynn most definitely believed in the use of trees on certain sites to be very central in the art of design and he was without question an architect who believed in very "high demand" architecture and strategies if he was given the opportunity to do it! Most of us also know what Flynn thought about the distance ramifications of golf and what that might do to golf architecture and design needs.
Many students of classic architecture sort of rue the fact that the "Golden Age" architects who did so many great courses and expected the art and profession of golf architecture to carry on and go well past them with creative and innovative designs in the future never saw that really come to pass. Some say it never happened. Many were expecting some sort of "connection" between the "Golden Age" and the "Modern Age" of architecture. Flynn may have been that "connection" that never really connected. Part of it may have been that he died in 1945 at 55. But the real answer probably lies in the Great depression and the lack of work and product.
In any case, Flynn had some serious roots in every way in the "Golden Age" but at the same time seemed to be a real innovator and clearly appeared headed in that direction. What would he have done if he lived another 25 years? If you study him, his thoughts and philosophies and his sometimes radical ideas you can get some indication, but again, I think there are some on here who wouldn't like what they would learn.
I've tried to get Andy Karff onto this site for two years but for some reason he hasn't come on. In my opinion, the real expert on William Flynn is Linc Roden though!
Interesting Flynn sidebar is he was also an excellent tennis player and taught the game early on--maybe the only really good golf architect who was ever into tennis.