PvP Defensive Team - Clarification Request

I would like to request that at least some level of the coding logic, of how defensive teams for PvP are being determined, be released to the players.

1 - I think we can assume that if you use a single team throughout an event... that's your defensive team.

2 - Many questions have already been raised about what gets put on defense when you use multiple teams... which one is considered "strongest"?

The issue that prompted me to create this topic, is the edge case between these two. Using the same three heroes, but one (or more) of them, using different builds. I've been running XPool mainly 5/3/5 in PvE, and switching him to 5/5/3 for the current PvP. Occasionally, I've forgotten to switch back when jumping between events.

So which version of my XPool is on defense? And why?