A good length ball is a type of delivery

Delivery (cricket)

A delivery or ball in cricket is a single action of bowling a cricket ball towards the batsman.During play of the game, a member of the fielding team is designated as the bowler, and bowls deliveries towards the batsman...

 in cricket

Cricket

Cricket is a bat-and-ball game played between two teams of 11 players on an oval-shaped field, at the centre of which is a rectangular 22-yard long pitch. One team bats, trying to score as many runs as possible while the other team bowls and fields, trying to dismiss the batsmen and thus limit the...

 that pitches at a distance from the batsman

Batting (cricket)

In the sport of cricket, batting is the act or skill of hitting the cricket ball with a cricket bat to score runs or prevent the loss of one's wicket. A player who is currently batting is denoted as a batsman, while the act of hitting the ball is called a shot or stroke...

 that makes it difficult to score runs

Run (cricket)

In the sport of cricket, a run is the basic unit of scoring. Runs are scored by a batsman, and the aggregate of the scores of a team's batsmen constitutes the team's score. A batsman scoring 50 or 100 runs , or any higher multiple of 50 runs, is considered a particular achievement...

. Furthermore, such a delivery is difficult for the batsman to judge whether to play on the back-foot

Back foot contact

In the sport of cricket, back foot contact is position of the bowler at the instant when the back foot lands on the ground just prior to delivering the ball...

 or on the front-foot

Front foot contact

In the sport of cricket, front foot contact is the position of the bowler at the moment when the front foot hits the ground just prior to delivering the ball. For a right-handed bowler the front foot is normally the left foot.-See also:*Grip*Approach...

. However, the distance from the batsman which is the ideal good length varies depending on how high and fast the ball bounces on a particular pitch. The pace of the bowler is also a factor, as faster bowlers will aim to pitch the ball further away from the batsman.