I've just come to accept that bruiser players are just better at their champs.....
When iwilldominate picks taliah and gets 24 kills and can't really carry the game he is just bad on her. Then the very next game picks camille and gets 2 kills and starts 1v3ing and ends up 1v5ing a game that was much closer..... he just knew how to play better on camille.
When fiora players have yet to post less than 15 kills in my games... they are just more experienced.
When mages and adc's scores look like 2-5 1-9 almost every game...... and assassins and bruiers are constantly 10-3 7-1 22-8. They are just more experience at their classes.
when the mobile tanky champions have more damage than the immobile squishy champions thats definitely a learn to play issue.