ARURF - Champion chance %

So i have been playing ARURF on the PBE for quite a while now and i have had the feeling that it is not totally random which champions are chosen for both sides. I have also noticed this with the other ARURF there has been.

It feels like champions such as Nunu, Shaco, Warwick and Orianna is there in 75% of the games while others such as Nidalee, Gnar, Janna and Leblanc is "picked" less often than everyone else. I know you have to count in the rerolls but i have not seen anyone get Nidalee or Gnar on my team yet even though no rerolls were used.

Am i the only one thinking this or does anyone else have the same experience?

Merry Christmas btw. ^^