So make the system smarter than the troll.
We can build a computer that can beat 1000 people at chess all at the same time. Hell, League's system can already keep track of when and where a champion kill happened, or when a turret/Baron/Dragon was killed, and who was involved in any of those cases. It stops short of tracking each individual minion and/or monster kill.
I think we can build a program that keeps track of ward locations, when it was placed, whether or not that location already has vision, how often it was used as a Teleport node, if it was killed prematurely and by whom, or in the case of Vision wards, if/when and by whom it was killed, etc.
We could probably also build a program that compares each user's personal MMR, so it can scale the score differences between players more fairly. "Yeah, you had a pretty bad game, but you queued with your buddy who's several divisions above yours, and all of your opponents were above yours as well. Your score is still going to be penalized, but not as severely as if you'd scored this on a level playing field."
We might even consider going as far as tracking specific champion abilities. How often did the Brand player chain his Blaze effects? How many axes did that Draven player catch? How many people died after stepping on one of Caitlyn's traps? Did Mordekaiser steal their carry, or their support? How much AP did Veigar farm with his Q?
Now, I'm not naíve. I'm actually a programmer myself, and I am fully aware of just how daunting a task this suggestion is. But the system we have now is just not good enough. It often rewards poor play because the player made enough smart plays to help their team carry them, or punishes great players who got bad teams, picked into bad compositions, etc.
It's an insult I take personally to know that I played 3 Shyvana games to get just barely <200 points more than I got from 1 Taric game, all because the Taric game was a victory and two of the Shyvana games were losses.