To follow up on my last thoughts about the rankings, keep in mind that the order in which the results are recorded actually matters for the PPG and tiers. This makes it difficult to determine what PPG you should have solely on the basis of W/L against various tiers.
As a simple example, consider the first recorded result of a season.
Situation 1: Both players start as tier E.
Winner gets awarded 7 points, loser 3 points => Loser gets bumped down to tier 2 => Winner’s points get bumped down to 5.
Result: Winner is tier E with 5 points, loser is tier 2 with 3 points.
Situation 2: Both players start as tier 2, winner’s tier gets adjusted first.
Winner gets 5 points, loser 1 point => Winner gets bumped up to tier E => Loser’s points get bumped up to 3.
Result: Winner is tier E with 5 points, loser is tier 2 with 3 points.
Situation 3: Both players start as tier 2, loser’s tier gets adjusted first.
Winner gets 5 points, loser 1 point => Loser gets bumped down to tier 4 => Winner’s points get bumped down to 3.
Result: Winner is tier 2 with 3 points, loser is tier 4 with 1 point.
Situation 4: Both players start as tier 4.
Winner gets awarded 3 points, loser 0 points => Winner gets bumped up to tier 2 => Loser’s points get bumped up to 1.
Result: Winner is tier 2 with 3 points, loser is tier 4 with 1 point.
So just with these 4 situations we’ve found two “stable states”, and two different ways of getting to each of them. Situations 2 and 3 even have the same starting point, but get different results depending on what order the tier adjustments are performed in. I haven’t included the last stable state for this setup (winner at tier 1, loser at tier 3), since it’s just symmetrical with the given situations.
Now consider what happens with the exponential increase in complexity caused by having hundreds of games. There are probably all kinds of various “stable states” we could find in the current rankings by shifting blocks of people up and down between tiers.
All of this is just to underline my earlier point: the PPG and tiers are arbitrary and don’t matter. What matters is your ranking compared to everyone else, which will not change significantly regardless of how the PPG and tiers sort out.