Oh goodie--another "Why isn't Eric McKnight Playing" thread!
The immediate answer is--your expectations were both too high, and unfounded.
The reason Eric was signed was that he is very athletic--despite also being very raw. Personally, I thought that everyone understood that he would be redshirting if Fred had a choice. Once he starts to develop some skills, and understanding of the game to go with that length and athleticism--watch out!
I suppose that if he works hard and keeps learning, he might see some spot/emergency duty late in the conference season--but I'm not etching that in stone.
Thanks for the enlightening "oh mighty god of 7000 posts".