I understand your point, but I don't agree with the term "agency" in that usage!
Why does agency necessarily mean "individual ability to determine winning." By that metric, the players who have the highest WARP in baseball therefore have the highest ... agency? But wait ... why wouldn't we just say that they have the highest WARP?
In other words, why are we using this one term with a completely different meaning ("agency") as a stand-in for another term (individual ability that correlates to a "win" statistic) when we can just say ... the individual contribution?
Because when we do, and we get away from the weird jargon ("player agency") we would immediately see that the rules of the game are what really matter- in other words, individual sports, because the rules only allow for one player, will always have a higher "player agency" than team sports.
Kinda like how people are defining "player agency" in these conversations. "Well, if a player can author the fiction, that's player agency. Therefore, the more authorship of the fiction, the greater the player agency!" If that's really what they're talking about, you don't need to use that jargon- just say, "This game allows more player authorship of the fiction."
See? Easy!