so the issue is not enough splash in those fights.
For a melee ranger
procs: Thousand cuts, Lightning strike, slashing wounds, giant killer
Tree: tree of electricity
normal: Your weapon swings
Procs: Sweeping strike, Vengeance, thunderstorm
attacks: Breathing room, closure, Baldeweaving, bramble wall
Tree: tree of roots
So, the issue isn't not having enough AOE damage, because every single one of the single target effects fire off of any AOE hit, depending if it fires on skill or not.
Slashing wounds will fire every time it hits, its not a HUGE amount of damage each time it hits, but it is consistent damage, I might change how it works (ie lower its amount and make it more stackable)
Thousand cuts fires on any hit on a monster, it does have a minimal internal cooldown so you don't lose all your counters instantly and it fires more like an actual attack, then a true rapid fire proc.
Lightning strike fires on skill hits, and has the smallest internal cooldown, simply enough time for it to let the animation fire again.
Giant killer: This one is a bit odd, the three procs will actually fire on any monster they hit, but only effect the unittype they are designed to damage. These do high damage and are noticable when hitting bosses.
Lightning tree: Have you actually watched how much damage this tree will put out? It uses YOUR dps not the tree's.
What is your build now?