Chaze doesn't hold well on defense because most players use chaze now. I feel 9/10 or 8/10 players in the top 10 of an arena shard use chaze, then it makes sense that players trying to break into the top 10 will have to beat chaze teams in order to get there. Hence, those chaze teams will drop out of the top 10.
It's been said on dozens threads over the past months that the issue with chaze is not that they're unbeatable arena gods, it's that they're arena gods who do too many things well with no drawback to their base stats