On her blog Super Effective Warhammer's favourite Portuguese Sara gives a great example of how you can be effective in a scenario without having to put out massive amounts of damage and by just doing something smart, something effective.
In her example Destro were being spawn camped by Order but instead of offering herself up as free renown she joined a couple of other players in escaping the farm and capping the BOs and, once capped, coming back at Order from behind and throwing a spanner into the works, kicking up a fuss and providing the initiative for the rest of Destro to push on and eventually win the scenario.
I did something similar last night. I entered Serpent's Passage a few minutes in to the scenario to find my Order compatriots scattered and fleeing back from the wreckage to our spawn point. We all got farmed for a few minutes until I decided to try and find a way out. I mentioned in /sc that I was going to make a run to the east and if Destro followed me everyone else should push out. I mounted up and ran east from Order's spawn point. Sure enough 5 Destro chased after me. When they caught up with me I used my Morale 2 AoE snare to slow them down and kept them chasing me under the rock bridge thingy in the middle of the two sides. They caught me in the end, and killed me of course, but as I died I could see Order pushing out from our spawn point. By the time I had respawn we had wiped them. What. A. Hero.
The morale of the story is not everything boils down to a DPS race and just a few well-placed moves and abilites can make all the difference.
For more tactical shannigans go and read Thrangis the Red's excellent post about the Nordenwatch scenario.