Thanks for the correction re lacrosse. To what extent does its systematisation reflect parallel developments in other field sports in the nineteenth century?I hate to disappoint you, but lacrosse isn't a hybrid of anything. It is literally a Native American game which was adopted by European settlers. It is pretty popular in New England (at least in Vermont, I think also other nearby states) where there are regular high school and even college-level leagues. Field Hockey is similar to lacrosse, but derived from an entirely different source, which just goes to show you that the 'phylogeny' of various sports is not easy to discern. I suspect that several of these 'field games' have heavily borrowed rules concepts. I mean, basketball, football, hockey (all types), lacrosse, etc. all share similar concepts of goals, goal keepers, offensive 'center' and 'wing' players, out of bounds handling rules, etc. Games like rugby and American football have diverged heavily from that model, but if you go back far enough they look more and more similar too.
On @EzekielRaiden's point more generally, I think he is comparing RPGs at a state similar to the early to mid nineteenth century re modern field sports, with those sports in their present ultra-codified and technicalised state. If you go back to the period when various forms of football were still emerging, with different rules about permissible kicks, handling, passing, etc, and different approaches to goal design and scoring rules, you might see more of the fluidity that still tends to be characteristic of RPGing. I think you see some of that same fluidity in games that haven't been technicalised (ie mostly ones played by children where there is no commercial interest in promoting technicalisation).