Rebounding skills do help with OREB's. Don't get me wrong when I say offensive ratings... it's a combination of RB, ATH and IQ that determines how many OREB's you'll get. As I've been told in the past though, the most important stat to RB is RB so it does come into play significantly. You also have to look at FG%... vs your opponents FG%... If you are hitting a high % of shots then your OREB's will naturally be lower than an opponent who is shooting badly and attacking the glass. The opponent then has more opportunites to get OREB's and may have more in total... that number can be misleading sometimes.