Truthfully,
isn't so bad as you might think, as he's normally easy to counter with high range poke, but you just had a poor match up. For instance, check out your team comp versus theirs.
low cc, low mobility outside of the adc, good poke on mid/support, but your adc is out ranged bot. You also have only one tanky champion in Malphite as you didn't build any truly defensive items (
actually could have done wonders for you). Teamfight wise you're at a large disadvantage because you have no way to retreat from a poor fight, but because your opponents also probably snowballed and got a lead most of the time, you couldn't set up any ambushes in order to get an ace and stabilize.
I'll bet that you personally also died a lot to being hard cc'd during your ult, as you can still be stunned during that, so a better item choice you could have made was
as opposed to
. That
that I presume you were trying to build also isn't quite so good on you if you don't already have some health to spare, so a better option could have been just getting
, or set up for Death's Dance with
.
Lastly, having the fervor of battle keystone may not be bad on yi, but to go raw ad as well is simply poor planning. Your passive may give you a sort of attack speed buff, but it is having high attack speed already that really make the ability be so deadly in tandem with that Keystone. Think in comparison to Yasuo or Fiora. Those are the sword users that kill with a few deadly strokes. Master Yi is the type to kill with a hundred strikes in the blink of an eye. Seriously, just listen to Master Yi fight and you can tell. He doesn't usually kill in 2 or 3 hits unless he's built critical strike chance.
The trickiest thing to advancing in League is learning each and every one of these little things about your champion of choice, in tandem with every other champion you happen to be placed with or against. And to be able to do so in the span of just a few precious minutes.