MDL in general and the MW rating system is brilliantly designed to keep you motivated, whether you want to play competitively (since the rating system and the '10-games condition' remove all those boring rants about stalling, run and rating manipulation) or just play casually and get good matches on good templates (what QM most of the time fails to do).
Unless they really love MME and don't care about seeing people with overinflated rating getting temporarily above them, the 1v1 ladder certainly fails to keep good players engaged for a long time.
There is however a design flaw which is annoying with the current implementation and would probably discourage even the most monomaniac MME fan : the Boston run pattern.
There are currently 2 players that I don't want to be matched with if I expect to have a fair rating. They both are good players, who rely pretty heavily on gambles/smart predictions and the outcome of a game against them is often unpredictible. That's fine, I like such opponents.
The issue is that after a while, they get bored of Warzone, stop logging in and start a nice boot streak. Which will only stop after 50 (!) boots to get them to a rating below 1000 in less than 2 months (both players generally have 5 ongoing games of course). If you are unlucky enough to have lost against them while they were active, your rating will incredibly suffer from it due to BayesElo.
That has been discussed dozens of time already I guess, but just removing a player from the ladder after a few boots would solve the issue.
(One of those players is obviously Boston, who has this interesting rating shape displayed above. The other one is that Dutch player -hello / later / KakkieG / Ricky87 who keeps creating new accounts with the same pattern. And you guessed it right, I lost twice to him last month :-(