Most baseball fans are familiar with the phrase, "he knocked the cover off the ball." It's a line that's usually bandied about when a batter crushes a baseball, when those exit velocity numbers are simply eye-popping. It is not, however, generally used when someone dribbles a foul ball up along the first-base line.

But Royals backup catcher Freddy Fermin defied that bit of time-honored baseball logic on Wednesday afternoon when he made contact on a foul ball in just exactly the right way so the cover, in fact, came off the ball. Fermin's roller dribbled to the on-deck circle where it came to rest by the foot of Nicky Lopez.

• Wackiest plays in baseball

The D-backs broadcast crew was all over the funky occurrence, begging the question on everyone's mind: "You may ask yourself, how does that happen?" color analyst Bob Brenly said.

He proceeded to explain by showing how the perfect point of contact had to be at the rounded back edge of Fermin's cupped bat in order for the cover to tear. Fermin also had to be well out in front of the pitch, which was an 87 mph cutter that completely fooled him.

Fermin, meanwhile, didn't know what had happened until he saw a video replay after the game.

"That's crazy," he said.

So now you know a little bit about the physics of tearing the cover off the ball, even when you'd least expect it to happen.