You need to watch the games again and pay attention. C Gates played with the first team offense till the 4th game. He was the starting Split End in the FIRST half of games. Chad Henne was his QB most of the time. The WRs were Marshall, Gates, Hartline and Bess.
After the first team got off the field, C Gates did play some but it was mostly Wallace/Moore and others. C Gates is being practiced and played in preseason games as our coaches expect/hope him to be a big part of our offense.
The reason Matt Moore has the one long completion to him is because in the 4th game against the Cowboys, Moore started at QB. In that game, C Gates again started at split end and Hartline started and played in the slot till the half.