I still don't know if I understand this. How does a string help a pitcher get a feel for a drop? I have heard of contraptions of setting up string in front of the catcher and trying to make the ball go under the string but even that has never made any sense to me.
The object is to throw the ball over the string and then have it end up low at the plate. We used a lawn chair between the pitcher and the plate, and we put a bucket on its side with the opening facing the pitcher. . She tried to throw the ball over the chair and into the bucket.
It was a challenge, but she enjoyed. It was fun.
The string/rope/chair does two things.
First, the pitcher must release the ball at the correct height. If a drop ball is thrown too low, the batter won't swing. Batters are looking for balls thigh high or above. If the ball is knee high, the batter will probably take the pitch.
Second, it helps the pitcher work on getting enough spin on the ball to get the ball to drop. If there isn't enough spin on the ball, the ball will end up thigh high or waist high. If there is enough spin, the ball will go into the bucket.
If you use soda cans sitting on the corners of the plate, then the pitcher can work on control.
The great thing about using a rope/chair is that the pitcher can see the results without the need for the PC or Daddy to evaluate the pitch.