NFHS Rule 1-6-3

[DaveASA/FED]

"1. to chase or follow after; pursue.
2. to go after and bring back; fetch.
3. Baseball. to retrieve and throw back (fly balls) in batting practice."

Above is from Dictionary.com for shag. IMO she is not there to shag balls, she is there to perform a defensive function of protecting the pitcher from being injuried while she has her back to a live ball. She is not there to retrieve and throw back balls, she is there to knock them down and keep them from rupturing a kidney by hitting the back of the pitcher, or killing her with a shot to the brain stem.

Scooby,
There is a chance that right or left fielder could in fact be in trouble of being hit also, if she is playing close to the line and there is a fly ball in foul territory that she goes for as the catcher releases the ball she could very well run into a throw in the back of the head, not as likely but possible.