The Hitting Zone
and the Hitting Arm
The "hitting zone" is the swing path or area where a player's racket can make contact with the tennis ball. How does this affect the hitting arm configuration—straight or bent?
Hitting the ball with a straight arm way out front of your body diminishes your hitting zone and leaves no room for error. Slightly miss timing your stroke, a minor error in judgement, a bad bounce, or a gust of wind is likely to cause a loss of control resulting in an error.
Take a look at the Roger Federer's forehand and notice how he can't really stretch further in any direction to make contact with the tennis ball.
As you can see, Federer is at the far limit of the hitting zone. If his timing or judgment is off by just a few centimeters the shot is likely to be weak or a mistake.
A Longer Hitting Zone
With a bent arm forehand on the other hand your hitting zone is much longer. Your forehand contact point can range from parallel to your body up to 2 feet in front without losing control.