In no universe is Faried, College basketball's greatest all-time rebounder and an NBA career Per36 11.9 RPG, an awful rebounder. At any position.
Charles Barkley, literally the Round Mound of Rebound, averaged 7.6 DRPG per36 for his career. Kenneth Faried averages 7.4 DRPG per36 for his career. Again, not an awful defensive rebounder at any position. For further reference, Hakeem Olajuwon averaged 7.9 DRPG per 36 for his career. Is he an "awful defensive rebounder" for a Center too?