Drop The Ball Meaning

(idiomatic) To fail in one's responsibilities or duties, or to make a mistake, especially at a critical point or when the result is very negative.

Example: 1996 Dec. 13, Peter Stack, "Tom and ‘Jerry’ Make a Great Team" (film review of Jerry Maguire), San Franciso Chronicle (retrieved 21 Sept 2013):
  The movie ought to sputter out here, but Crowe and Cruise don't drop the ball.