Like I said, well argued theory Gary and Greg. I would only push back on one point: the Dodgers were not
exclusively known as the Robins in 1920--or any other year, really.
In fact, there's never been a pennant bearing the name "Robins" to my knowledge. The 1916 NL champs pennant I previously reproduced on
Pennant Factory ID'd the team as "Dodgers" (see:
https://pennantfactory.weebly.com/bl...champs-pennant ). Moreover, the 1920 World's Series program identified the team as "Dodgers" despite the fact that Wilbert Robinson himself was prominently featured on the cover. Both items were made during the height of Robinson's popularity; yet, the name "Dodgers" was featured on them.
I only wish your theory got us closer to ID'ing the mystery maker behind these grommet pennants.
I also spent some time looking for HoF dedication photos from the 1939 grand opening, hoping to find a spectator or two waving a pennant--but came up with nothing.