The difference in reaction between having a pin close to the val , or one below the fingers is a physical one, not so much a ball one. See if you can follow what I am about to say.
If you place a ball in your hand and make like you are about to release it, immagine the top of the weight block being in your palm (pin below your fingers)and immediately start to tumble as it comes off your thumb then fingers.
Now immagine the same senario with the pin above your fingers, the weight block is now more vertical and resists going into a tumble for several feet past where the pin below the fingers started to rev up.
Now immagine the same senario with the pin on or close to the val, the weight block is almost completly vertical and resists even harder to the forces placed upon it by the fingers at the release for several feet more.
That is why it is ultra important to stay 1 1/2" away from the val unless you are 100% certain of your pap and have a consistent enough release, otherwise the pin could be on the opposite side of your val depending on how you release it, and weird things could happen, like flare reversal and the ball doing different things each time you throw it.
Think if you were in that commercial where they tell Grandma to tuck and roll, with the pin in the palm, your weight block is at it's shortest height and tumbles easilly, now toss grandma out the train while standing and she doesn't tumble as quickly and probably doesn't survive that commercial.
