Effect of Surrender on Elo Points
Another seemingly confusing matter, is surrendering and how it affects the ranks of Players on each team. You can only surrender if a Teammate leaves (and receives cooldown for doing so), and there are people claiming that if you surrender you will not lose any Elo Points which is not true.

This subject can be observed from two different point of views, first I will describe what happens to the player who leaves a match. A player who leaves a match will keep any changes to his Elo Points until the points round he leaves. For example if a player loses the first 3 Rounds of the match and rage-quits, he will only lose the points for those 3 rounds and how his Team performs afterwards will NOT affect that individual at all. Same is applied if he wins some rounds and disconnects for any reason. So in a nutshell, if a player wins a round and leaves, he will get some points (although very little) and vice versa. Please note that the finished game will still show up as loss in history, the extra rounds won or lost whatsoever have no effect on his Elo Points.

But what happens to the remaining players is a bit different than normal matches. From the round a player leaves, they will have the extra Elo Points removed from their total points and all points gained will be distributed only among 4 players. The BOT will have 0 Elo Points, and will never gain or lose points. An MVP gained through a BOT control will result in Elo Points being normally distributed among the 4 players (the game will assume no one gained an MVP and thus no one will gain the EXTRA BONUS). Please don't confuse this with less points gained, they will still take the full amount of points from the enemy team, however it will be more evenly distributed among the 4 remaining players.

So if a player leaves, the remaining 4 players of that team will gain significantly more points for Round Wins and the enemy team loses a significantly more points for Round Losses. That is because, it is highly unlikely for the 4 player team to beat a 5 player team (based on Elo; BOT is not considered). So in a sense, it's not really a good idea to surrender IF you're strong enough to Win ROUNDS. However, the moment your team surrenders, any extra rounds out of 30 will be forfeited and all players will keep the changes to their Elo Points.

To sum it up, if you lose against a team with a leaver, you will lose a lot more Elo Points and if they surrender everyone would keep their current ratings. Thus, it's not uncommon for someone to derank even if they win through a vote surrender. Because they might have lost enough rounds and thus enough Elo Points for a Demotion. Everytime a player leaves, the Elo Rating System will be revised for the remaining players, no matter how many they are.
Effect of Kick on Elo Points
The effect of Kick is the same as a normal leave, the only difference it that it won't unlock the option to Vote Surrender. So if a Team votes of an individual player, they will only lose the advantage of keeping their current points through a surrender. They will however, gain significantly more points if they Win Rounds which is unlikely.

The voted-off player (doesn't matter if he receives cooldown or not) will keep any changes made to his Elo Points until the round he was kicked and the rest of the match will have no effect, even though it shows up as a loss in history. If a player is kicked by 4 other players who queued together, the whole match will be nullified.

Source: https://steamcommunity.com/sharedfiles/filedetails/?l=english&id=312582297