How does a baseball defensive position illustrate mathematical structuralism?

In the philosophy of mathematics, mathematical structuralism—as developed by Michael Resnik and Stewart Shapiro—posits that mathematical objects are not independent entities but are instead positions within a structure or pattern.1

A baseball defense serves as an effective analogy to clarify this concept. In this model, the defensive positions (such as shortstop, pitcher, or right fielder) represent the structure itself. These positions are defined by their roles and their spatial relationships to one another on the field, rather than by the specific individuals who occupy them.1

When a player like Honus Wagner played shortstop, he was a concrete object filling that role. However, the "shortstop" position remains a structural role regardless of who is playing it. Similarly, structuralists argue that a number, such as 4, is not an object with internal properties like weight or height; rather, it is merely a position within the positive integer pattern, defined solely by its relations to other numbers, such as being between 3 and 5.1