From a kayfabe point of view, the Royal Rumble is an unfair match, and therefore a pretty bad way of determining who gets to go to WrestleMania. The higher number a competitor draws, the less time he has to spend in the ring, and therefore, the better his odds of winning. Therefore, the #30 entrant (usually the last one) has the best spot in the match. The Undertaker has drawn #30 a record three times, but Big Show is close on his heels with two (2009 and 2012). If Show enters at #30 again this year (which is admittedly unlikely - that draw will probably go to Triple H), he'll tie Undertaker as the luckiest competitor in Rumble history.