How are win odds calculated?

Test Your Might

It is baffling me you would think that it’s calculated using the number of wins a player gets, their win/loss ratio or yet I’m looking at a single man with 1649 wins and 613 losses that I seemingly have a 72% chance of beating, and another man with 380 wins to 260 losses that I apparently have an 18% chance of beating. It absolutely doesn’t seem to generate any sense.
Unless, of course, it’s calculated by factoring in the stats of every player you have beaten/lost to, but this sounds a bit too intricate.
Am I overlooking something obvious or are these win odds percentages?
EDIT:
For those of you looking for the response, the overall (unconfirmed) consensus is that it is calculated with a method similar to the Elo rating system which calculates skill based on who you struggle e.g. you may have more skill points beating good players and shed less losing to great players and vice versa.
EDIT #2:
It is definitely an Elo-based points system; I have just noticed there is a”Score” column to the player match leaderboard these points have to be given/removed dependent on how many your opponent has.

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