The Athletic: The inside dirt on infield dirt: MLB addressing its ‘dirty little secret’ in wake of new shift rule [$]

It turns out that all big-league infields are not created equally. In fact, they’ve never been created equally. This sounds crazy, right? But multiple sources have confirmed it’s true.

There is an obscure rule in baseball’s official rulebook that mentions what those infields are supposed to look like and where you’re supposed to find — and not find — the infield dirt. But guess what?

According to sources familiar with all of this, that rule has never been thought about much, let alone enforced. So in some major-league parks, the infield dirt extends deeper than in other parks. We promise we’re not making this up.

And there is no rule in the books dictating where the inner edge of the infield dirt should be located. So in virtually all parks, that inner edge of the dirt takes on a slightly different shape and location, based more on aesthetics than math. Seriously.

Oh, and one more thing. You know the dirt/grass line around the bases? That can be placed pretty much anywhere and sculpted however the grounds crew enjoys sculpting it. This really happens. And you would be amazed how many people who work in baseball are completely unaware of it.