The main problem is that it is easy to smurf at low levels and win everything but at the higher level everyone are strong, as such winning is much harder.

Out of 64 people playing the game, 63 don't reach level 7. Reaching level 11 is one out of 1000. So you are battling an increasingly narrow group of players as you level up, eventually your win rate will be 50/50 unless you reach to the top and dominates almost everyone else...