The Bills were in a difficult situation in all the three rounds when there was a run on WRs right before them that pretty much took away any chance on them to get a WR. I am sure if Moore, Pickens etc were on the board at our pick, we would have selected them.
Additionally, the Bills have already picked McKenzie and Crowder in FA....so they were not going to invest a high pick on WR unless they fell to their draft position.