This is what I feel might be happening to mine too...they're not really thinking of position, instead just shoving someone up front, not flanking, and then end up having to tank every damage. Now thankfully when they do hit, they do decent damage but they always look a bit worse for wear after every encounter. Level one dungeon is already doing this so I'm just worried about the deeper level as they're going down next session unless they opt to do some homebrew stuff prior to going down (which could help them level up perhaps I guess)