Great read, thanks for posting!
Minor stats comment: Fig (5) is a little concerning because each curve represents a different population of teams, so it isn't a very clear way to show the trend of increasing performance as teams have attended more and more events. It is unclear to what degree teams from the left-hand side are moving rightwards as they attend more events or if most of those teams simply aren't included in the next curve. While it can be surmised by looking at the right-hand bounds of the distributions there are some performance increases, the graph would more directly support your point if a single population of teams (perhaps the 304 that competed at 4 events or the 765 that competed at 3) were tracked across their multiple events instead.
Edit: Please disregard the second part, I had misinterpreted the next figure
