A balk is any illegal motion by a pitcher on the mound executed in an attempt to deceive opposing the opposing runners and batter. While generally called by the home plate umpire, any ump can call a balk.

The balk call is generally one of the most confusing in baseball, as the infraction often looks fairly innocuous to most observers. Likewise, some dramatic movements by a pitcher may draw chants of “balk!” from fans but not be called as such by game officials.

In the end, it is the umpire who decides whether any particular motion is a balk, but there are some telltale movements that tend to result in a balk call.

Here is a quick rundown of some of them …

Quick Return

A quick return happens when the pitcher delivers the next pitch immediately upon receiving the ball from the catcher, with no setup. The intention is to catch the batter off guard and record and easy strike.

Faking Throw to Unoccupied Base

The idea here is for the pitcher to maintain possession of the baseball while making the opposing offense think he has thrown to a base. That could potentially allow the pitcher to catch another runner off base, or to deliver a pitch to the unsuspecting batter.

Mimicking Pitching Motion Without the Ball

The gist of this one is that a pitcher can’t make a “pitch” without having the ball in his hand. The reason a pitcher might do this is to make the runners think he has the ball, when, in fact, another fielder has it. That could lead runners to leave their bases and be subject to being tagged out.

Failure to Complete a Pitch Motion

This occurs when a pitcher does not release the ball after making his pitch motion, which could lead to an errant swing by the batter and runners leaving their bases.

Pitching While Facing Away from the Batter

The obvious motivation here is to be able to deliver the pitch when the batter is not expecting it, and from a location the batter can’t track. Baseball’s rules clearly state that the pitcher must face the batter.

Delivering a Pitch When Not in Contact With the Rubber

This goes for any motion associated with a delivering a pitch, such as setting and stretching. Basically, if the pitcher makes a pitch, or goes through part of his pitching motion while not touching or standing astride the pitcher’s plate (rubber), he’s subject to a balk call.

Conclusion

The balk rule is one of the trickiest in all of baseball, and the call — or non-call — always leads to a mix of boos, cheers, and confused faces.

You can read more about the balk in the Official Baseball Rules maintained by MLB, but be forewarned — you’re likely to still find yourself somewhat bewildered the next time a pitcher makes some funky movement on the mound.

Trivia

The record for most balks in a single game belongs to Bob Shaw of the Milwaukee Braves, who committed five infractions in a contest against the Chicago Cubs on May 4, 1963.