MBsocfan is exactly right, raise your standards of play, dont change the size of the goal to get more goals, thats gay. Also, if the defender is shielding the ball he is obviously in better position, so i would say he has possession, if he has possession he has every right the shield the ball, i do this on offense a lot of times until i have a clear pass, thats not obstruction if he's at the ball first and has enough time to position himself to shield the ball, ITS LEGAL;)