I just played nice game 24 min duration, we had several big fights.
Finally my random team won, and I got = +1 MMR . It is shocking outrageous!!!
But other times, when certain people leave instant, I need to close the game and I loose -9/-24 MMR. And this happens sometimes 5times in 5minutes because of somebody does not want to game.
What do you think? Is it fair how MMR is computed?
i’m not saying i like everything about it (ignoring other issues) but it depends on multiple factors including the MMRs of the other players, the duration (seems to be a factor), and probably other things. If you win an easy game that you’re expected to win, possibly because you have someone significantly higher in MMR, you’re not going to gain many points, and if you lose such a game, you will lose a lot (because you are expected, statistically, to win). You cant just say “oh i got 1 mmr and lost 10” and cry that it’s unfair.
Again, that’s not to say there aren’t issues, but it isn’t simply random or saying “I want cat to lose lots of MMR and some other guy to get lots”
Like you said depends also on duration.
If a game lasts 1 hour , and is a hard win, than 1 MMR is just outrageous ! Blizzard is having fun of us !
Well if you actually only got 1 MMR for a game, that means that the system, in matching those players into the game, expected that your team was almost certain to win. If it ended up being a difficult game, that would mean you were underperforming for your rating.
IF the system expects that, than also the system can interchange 2 players in order not to expect that.
Eg. ABCD vs EFGH , can result that team ABCD almost sure wins they are too strong;
so then system could interchange, and pair: AHCD vs EFGB than !
And put a minimum, because when eg. Shockandawed leave, one after another 5 games, in 24sec/(game+search) x 5 games = 2 min, I am loosing like -200 MMR without actually playing the game - that’s really not fair.
Then (if the Goddess Agrees) 1x normal game and after 30 min I gain back +1 MMR. 
This is actually the biggest issue right now (aside from the match recording issues). It does not always balance the teams correctly. It’s not really the MMR calculation that is wrong, it is the matching system.