Pvp defence battles - xbox

I have a few questions about whats happening now.

Looking at the top 100 I now see a player with more defence battles than games played.

How are players selected for defence battles?

One poor soul is well over 300 whiles others are barely 100.

Thats a lot of points, apparently unrelated to games played.

If players are getting selected for more defence battles than games played then minus points or zero must be possible surely?

Is there some form of handicap being applied now, and is it related to level?

Bizarre things in defence battle selection.

I would very much like the answer to this as well