Here's a way that might help. Suppose there are two pieces of paper in front of you. One of them is a genuine $5 bill. The other is a perfect counterfeit. In fact, suppose that it was illicitly created by the very same equipment that created the real bill. The point is that the difference between the real $5 bill and the fake isn't a matter of the physical properties of the piece of paper.
A similar point holds for the home run. There are certain things that have to happen physically for something to amount to a home run. But with a little imagination, we can tell a story on which what's "really" going on has nothing to do with baseball. It just looks for all the world like a real baseball game. But to be a home run, the physical events have to be part of an honest-to-Babe-Ruth baseball game. Without the right intentions, rule-following, etc., no set of physical events amounts to a baseball game. There are physical regularities in a baseball game, but some of the most important things have to do with explicitly, intentionally, following a set of rules or norms.
Does this mean that there's something spooky about signing checks and playing baseball? I don't think that's the intent—or at least it shouldn't be, Physics has lots to say about the physics of spheres colliding with bats and so on. But physics has nothing to say about stolen bases, designated hitters, and the like.
Also: while it may be true that the immediate physical facts about the ongoing events in the stadium don't make something a home run, facts about baseball "supervene" on broadly physical facts. The difference between a real home run and something that merely looks like one may not be found in the physical properties of what's going on in the moment. But it's pretty plausible that there can't be a difference between a real home run and something that just looks like one unless there is some physical difference somewhere in the history of what's going on right now. Even if some of the things that make home runs home runs have to do with minds, it doesn't follow that mental facts float free of physical facts.
That said, and I assume this is somewhere in the ballpark (heh...) of Prinkard's point, no amount of sheerly physics-y knowledge will add up to an understanding of baseball. Or paying a bill. Or meaning what you say. Prinkard is pointing to the way that norms, rules and practices enter into making certain things and events that things and events they are.