I feel like I might have already written a post about this once. But who cares?
I'm intrigued by the way sports evolve, and especially whether offense or defense improves faster. Look at basketball: from its invention when games had final scores like 6-2, to today when even high-school teams break 100 points sometimes. Basketball offense has improved much more than basketball defense has.
Generally speaking, basketball and American football evolution has favored offense, while baseball, hockey, and soccer evolution has favored defense. Anytime a league needs a rule change to increase scoring, it's an indication that offense evolution has been outpaced by defense evolution.
I find it interesting that this relates pretty well to pee-wee versions of the game: little kid basketball games are lower scoring than professional games, while little kid soccer games are higher scoring than professional games. Think of kids as modern-day representatives of proto-players.