You obviously forgot to use your trinket more than 3 times in the entire game.
only 3k more gold than skarner
I want to say positioning and micro'ing may have to do with it.
Like for example my last game I just played as Caitlyn, I trapped immediately when my Support Blitzcrank landed a hook, which led the target to the trap for a root and Headshot then following with a 90 Caliber net for another Headshot.
So maybe it has to do with melding you and your teammates kits as best as you can.
Also I want to say positioning may have to do with it too.
Again going back to my Caitlyn match, when I was low on HP I pivoted around my teammates while an Enemy Urgot was using his W on me, that way rather than have him target me he's targetting someone else, like my Support Blitzcrank I was talking about earlier.
Then there's nuances like input buffering and flash channel cancels that the game also considers for grading. They do have the data in stats which probably aggregates it's data from replays. So I'm sure the game knows.
I've done it on Jinx and Sivir and Varus
the trick is to have the mentally disabled as your lane opponents and to somehow be 7/0 within 10 minutes and get the last hit on dragon and have them surrender immediately at 15/20 so your gpm/expm are the highest.
shouldn't have died
Busty pointed out ward score, but IIRC you're supposed to be getting 10cs/min so that was a little bit off as well.