Ozil may not necessarily be the best player in the world. This statement can be very relative to context; is he the best player in the current world rankings? Best player in history? With the amount of sportsman not inducted into the professional level, what if the world's best is simply idling within the semi-professional ranking?
Ozil is a very good player, one of the best playing in the world today, but Messi and Ronaldo are both insane athletes. Those two could be the best athletes alive at this point in time. Ozil could be one of the best in the Premier League, but not in the world.