I would think that the most likely cause is poor pollination.
If you had cold or wet weather dureing the blossom period of your grape then it may well be that the blossom was not viable and as a result ...fruitlet drop.
I did get some answers elsewhere but not from the Helpful Gardener. I went to U.Mass Extension and they helped. There were several reasons that the grapes were dropping off. One was not enough sun, another too much rain, yet another was not proper drainage, or not the proper pH. So you'll have some homework to do to find out why your grapes are not doing well.
Thanks Jona and Diane. It has been EXTREMELY rainy here over the last several weeks right so that makes perfect sense. I'm definitely doing some homework this weekend to see how I can bring them back to life.