This can be effective because the quarterback usually does very little after handing off or pitching the ball to the running back on most plays, and the defense might not be expecting him to be used as an active receiver.
If the linebackers and/or the defensive line are fooled and believe the ball carrier is attempting a run, they will pursue the runner, abandoning their pass defense responsibilities and thereby leaving pass receivers uncovered.
The play almost completely relies on the element of surprise and better coaching has resulted in defensive backs being instructed to stay in coverage until the running back with the ball crosses the line of scrimmage.
However, certain teams and players do successfully run the option one to a few times a season; used sparingly it can be effective to make a game-changing play.
In modern professional football history, a halfback has only thrown more than one touchdown in three games: halfback Paul Hornung of the Green Bay Packers threw two touchdown passes in a 1959 NFL game against the Los Angeles Rams; utility player Gene Mingo of the Denver Broncos threw two touchdowns as a halfback in an American Football League (AFL) game against the Buffalo Bills in 1961; and running back Walter Payton of the Chicago Bears threw two touchdowns in a 1983 NFL game against the New Orleans Saints.