Imho the best way to solve this problem is to simply grant a ton of experience to top3 winners depending on their power.

Something like that if you are 93k power in a field of all level 91 and the 2nd strongest is 79k and the 4th strongest is 68k (happened to me today) then you are instantly made level 92.

Seriously, you have to do something to avoid this problem and the best way is to forcefully grant EXPERIENCE as reward to top3 people.