Baseball: Definition of "swing"

I’ve been watching baseball for years and I realized that I never knew the legal definition of a swing and what criteria an umpire uses to determine if it’s a swing or a checked swing. So I decided to look it up in the MLB rules. And it’s not in definitions, not in The Batter . At least, nowhere I could find.

I have heard various things from fellow fans:

It’s a swing when. . .

the bat crosses the plate
the bat crosses the foul line opposite the hitter
the hitter breaks his wrists
the bat crosses in front of the batter’s wrists

So what’s a “swing”? I’ve got plenty of opinions so I don’t need more; come with a cite!

Usually, it’s when the hitter breaks his wrists. The batter is allowed to move toward a bad pitch without penalty (if the pitch is a strick, it doesn’t matter if the batter swings or not), but once he breaks his wrist, he’s considered having swung at it.

I am far from a baseball expert but in Little League, we also used the rule of the break of the wrist.

Note that the other three things you mention make no sense as a determinating factor.

  1. The ball crosses the plate. That means it’s a strike whether the batter swings or not. Every strike would thus be a swing under this.
  2. The bat crosses the foul line opposite the hitter. – If the ball crosses the foul line, it’s not over the plate and a ball. But that would happen with any outside pitch for a ball, even if the batter is motionless.
  3. The bat crosses in front of the batter’s wrists. This is just another way of saying “the batter breaks his wrists.”

It’s somewhat tautological, but a “swing” is whatever the umpire thinks is a swing. There is no official definition of it.

For ball-strike purposes, there is no such thing as a “half swing.” Either you swung or didn’t swing.

Bunting at the ball and missing it can also be considered a swing, but sometimes it isn’t.

This is one of the vaguest areas in baseball rules.

What? The OP distinctly type “bat;” you even typed “bat” yourself in your second line. Your explanations, however relate to the motion of the ball.

And there it is.

It’s kinda like balls and strikes. Yes, there is a book definition, but a strike is what the umpire calls, period. And the pitchers/batters don’t really care. The ump could have a strike zone the size of a hat or be calling it a strike anywhere nose to toes, dugout to dugout; as long as they are consistent in the call, the players will quickly adjust to it.

The closest thing to a definition is in 2.00 Strike (which is relevant – other than a swinging strike, when do we care whether or not it’s a “swing”?): a strike is a pitch “struck at” by the batter.

So there you go. Did the batter “strike at” the ball? If yes, it’s a swing.

The rule-of-thumb guidance I’ve been given in my umpire training relates to check-swing appeals: if you’re the base umpire on the corner, and you saw the end of the bat point at you: he swung.

FWIW, the MLB announcers I’ve heard all seem to use the same terms when describing a “swing” or non-swing.

Go around

Turn it (the bat) over.

Holding back.

Checking his wrists.

Turning over refers to the rotation the bat takes when one fully swings. The other terms obviously refer to the motion of wrist-breaking.

MLB announcers are practically as clueless as the average fan when it comes to the finer points of the rules of baseball. (Joe Morgan, I’m lookin’ at you…)