I've found that the best way to win with a weird or weak comp is to say at the start of the match, "We're probably gonna lose this with our comp"
You'd be amazed how much of a change in everyone's mentality that causes when I say it. I think that pointing out that your comp has a weakness causes everyone on your team to be more aware of the shortcomings of their comp and their champions and so they work harder to avoid or overcome those weaknesses resulting in you winning. Weird I know.
Happens more often than not...
once was Tristana top for easy S ranks and we had a singed/Annie bot lane.
We still won.
The hell is that KDA