A fielder is given an error if, in the judgment of the official scorer, he fails to convert an out on a play that an average fielder should have made. Fielders can also be given errors if they make a poor play that allows one or more runners to advance on the bases. A batter does not necessarily need to reach base for a fielder to be given an error. If he drops a foul ball that extends an at-bat, that fielder can also be assessed an error.
Defensive errors are a factor in some statistical equations. For instance, batters do not receive RBIs for any runs that would not have scored without the help of an error. And pitchers are not assessed any earned runs for runs that would not have scored without the error.
The league leaders in errors are typically shortstops and third basemen, who have to deal with a wide array of tricky ground balls and tough throws across the diamond. There is no classification of errors either. So a shortstop who makes a nice play on a ball but throws it away, allowing the batter to advance to second, is given an error, much in the same way an outfielder would be if he dropped an easy fly ball.
In A Call
"blunder," "booted it," "miscue," "mishap," "E"