And I've seen a 6k hp premium adventurer lose 4k hp in one rounds. In your example, if the attackers were up 35:9, why didn't they take the flag? Answer: poor strategic analysis of the situation and not being aware that they weren't killing them fast enough. If the defenders won, that wasn't because of the advent bonus, it was because the attackers screwed up.I've seen battles won by 9 adventurers in the tower + a few snipers against 30-35 attackers, if anything needs to be nerfed its Predator's cloaking device.
If you say they didn't have the health to take the flag, then that completely changes the situation, and your 35:9 leaves out crucial information.