I love that you took the time to call me out, that your logical in your stance. I dont get offended easy so no harm mate. Lets go over some of the basic assumptions for Elo derevitives.
First up. Who your playing matters. If I put you into a boxing Ring. Who do you think you will beat in a fight? Opponent A. A 4 month old child. Opponent B. A terminator Robot from the future.
The statistics generated are heavily skewed by skill gaps. Beating some one in chess with 2 moves is possible... but only if White makes the literal worst possible moves in the game back to back.
Second. K factor. Elo and MMR systems are not expected to be remotely accurate at low data. Uncertainty for reliability of rating is a big deal and core part of them. That means that the lower your # of games the Higher your raiting will adjust. As you generate more data points the amount of points per match you stand to gain or lose is lowered. You will see some deviation of Arpads adjustment formula which looks like this. Rn=Ro+K(W-We) 100% out of 1 game? not that impressive but 99% out of 100 games? that shits actually pretty impressive.
The biggest issue with stats is the # of variables and the fact they don't work unless subjectively judged. Beating some one in 2 moves for chess does not make you a grandmaster... it however is statistically the lowest possible # of moves you can win with.
Karth who hits R every time its off CD will out damage the player who saves it to cast for a moment that helps team. Tower and OBJ damage alone does not necessary win a game and the only way to really judge that is if you take the context of each individual game. Automation does not do great job for this because Worthless and Meaningful stats overlap.
A majority of ability's are better saved for smart usage rather then spammed, but spam tends to put more stats on the post game lobby. Its effectively far easier to play for stat padding then to play to win.
Not all champions will damage towers the same, or objs the same. Their metrics of sucuess will be things like vision or CC, but those are statistics that can be faked very easy to an objective automated system.
At the moment, The only thing that matters is your results and who your playing. Statistics that cant be faked.
My opinion on how riot makes their Titles represent skill are built on MMR principles. I understand how you could do a population system, but its shitty because its weaker and you cant go inactive with out sinking. The best way I am aware of is to set them to be accurate reflections of a MMR range at low uncertainty. That way when some one hits the expected # of games to reflect low uncertainty their Rank and their MMR overlap. So you slant gains to try and make Rank = MMR. The lower the uncertainty the closer the two variables get. But because you never lock an account down, recent history should always be able to shift the slant to a value that reflects how well your playing in your assigned MMR range.
The performance scores your talking about would get skewed by skill gaps. They also have to be champion by champion. You also kinda need to account for matchups impacting stat results. Unless its an arbitrary value then odds are Population will be used for averages which is not a stable metric. It shifts, literally on a day to day. Getting 4000 damage to X objective on Y champion will be more or less useful depending on how many players are on that champ and what they are generating That finite number off averages shifts constantly.
To many possible combinations, to many overlaps between good or weak stats that impact a game. End of the day MMR remains the best system because fundamentally Skill impacts your ability to win in any game where skill influences wins.
Please. Call me out again if I said something provably wrong or if you think I goofed something, or if I was unclear or failed to explain it adequately. I truly enjoy discussions with logical humans.
My goals this post. Help ya get why Gains are slanted. Show why stats are generated by skill gaps and unreliable with out context of each match.