Wayne:
I guess without anything specific it'd be hard to know what Flynn was doing out there at that time.
I guess we should be careful how much stock we put in the so-called "agronomy letters" between the Wilsons and Piper and Oakley, even though the length and quantity of their correspondence (maybe 2000 letters) seems remarkable and seemingly unprecedented because of that.
What we don't know is whether or not Piper and Oakley were carrying on the same type of intensely developmental agronomic experimentation and correspondence with others at the same time they were with the Wilsons (Toomey and Flynn). Perhaps we should ask the USGA Green Section if they have any other files from others around the country who were corresponding with Piper and Oakley the same way the Wilsons were for the same amount of time and at the same time.
The way the death of Frederick Winslow Taylor seemed to inspire them to collect and disseminate information which morphed into the Green Section and the Green Section "Bulletin" as well as inspiring Piper and Oakley's book certainly seems to have begun with Hugh Wilson (and we can't forget that Piper or Oakley initially asked Wilson to write a book on agronomy, right?).
And we certainly know that in Hugh Wilson's mind there was no greenkeeper as good and as economically efficient as William Flynn. What I've never completely figured out, though, was exactly when Flynn may've given up greenkeeping as to real active involvement and become totally involved in architecture. I guess one way to tell would be when Joe Valentine became Merion's official greenkeeper. But even with that I think Flynn continued to oversee him for a period of time.