What has been said plus we were not good at it in Chico's offense either.
Guys aren't beating their defenders off the line (there are a repertoire of moves that receiver should have, otherwise the DB picks up on the one move and just sits on it)
Guys aren't fast enough, or are being forced to the boundary
Guys aren't creative enough in their route running to deceive DBs
Guys aren't getting out of their breaks fast enough. This limits the amount of separation you're supposed to get, if say you run a drag or shallow cross
As has been said, Thaddeous is a physical receiver, and on top of that has he's got a repertoire of moves, and is a good route runner. Additionally, as a Y receiver, he has routes designed to attack soft zones behind the LBs and in front of safeties over the middle of the field.
This should change once we get into conference play.