Analysing the average number of rounds across platforms and ranks we immediately see that in general the higher the performance level, the longer the game. As players progress with their skills they are less prone to be dominated and (in case of MM games) stumble into a smurf. While playing on Silver level, very one-sided score lines are a frequent view, which doesn't happen that often on e.g. Legendary Eagle where players tend to come prepared for games and be able to win at least some rounds. It is also the most common to forfeit games at lower levels, with highest probability among unranked players.
Small round counts in matchmaking games can be also attributed to lower motivation. This is especially visible when compared to FACEIT. In general, players are more competitive there, so even on level 1, they are less prone to give up and just throw the game that on any MM rank. Here again the number of rounds played per match rises with performance, but changes are less significant especially at levels 6-10. The only very strong shift happens between levels 3 and 4, as from 4 upwards we see very few surrendered games.
Sudden drop at a highest level in Matchmaking games comes from higher number of cheaters than in other games. Unfortunately, even for players that work hard and try to improve with GGPredict this is a big issue. At FACEIT level 10, the drop is not very significant, but we attribute it to higher number of games played daily by players on that level and fatigue.