First part, I am not in bronze, i am in gold, so i queue with a plat or gold adc, and we get mostly golds. But my golds will feed 10-20 kills within 10 minutes, a fed gold player, with that many kills, game over (usually).
Coming off 5 straight losses atm, had to play top in 3. Still lose, not my best roll, best on team though, positive KDA, low deaths, near most farm each game, towers pushed to inhib, etc.)
If i being paid to work on matchmaking, i would spend that time, but i don't work for RIOT. But since you ask.
Their is enough to determine who is playing what rolls very easily. Who starts/kills more in jungle, who starts/kills more farm in what lane at the start, who ran support comparatively to the adc, or you can recognize you have a kill lane when both run kills style and share farm.
So given that. (Assume 30 minute average game)
Top-Mid-ADC:
+3 for kills, +1 for assists, -2 for deaths
+1 per 18 farm
Support-Jungle:
+1 for kills, +3 for assists, -2 for deaths
Support only:
+1 per 56 farm killed in close proximity by team mate
+1 per 400 healing
Jungle only:
+1 per 3 large camps
All:
+1 per 250 Damage to champs
+1 per 1000 damage to other
+1 per 500 damage taken
+1 per 5 seconds attacking tower
+1 per 1000 healing
+1 per 6 wards
+1 per 3 scans
+1 per 3 oracles (i don't remember exact timers here, should be set up appropriately)
Math for modifiers:
-Kill/Deaths within first 2 minutes x2
-Kill,Deaths within first 10 minutes x1.5
-Kill/Deaths within 1 minute of each other additional x.25 per death, compounding, decreasing counter each minute with no death(30 seconds for kill)
-Kill while outside starting lane (roaming assist/kill) pre 10 minutes x2
Game ending modifiers (given statistical standing comparative to all league players, my numbers are hypothetical)
under 50 percentile no bonus
50-60 overall bonus +.1
60-70 overall bonus +.2
70-80 overall bonus +.3
80-100 overall bonus +.5
in the following fields
Kill participation %
K+A/D Ratio
Gold (compared to specific role)
You get the idea. Should have 100's of pieces but it can be done. that's off the top of my head in 10 minutes. Give m a paycheck for the week, 40 hours, every bit of historical data RIOT has access to, and i could probably bang out a more effective Ranking system than Win/Loss. Give me another 2 months of PBE testing and feedback/collaboration, and you have a job riot should have done years ago.