Have you considered the fact that you are only good enough to be in tier whatever of sapphire, hence the matchmaking is working by keeping you there?
I mean if you are better than t3 saph you will eventually get through t3 by carrying one or two bad game matches and then just winning the others with (solo or team q, just a matter of time and maybe a little bit of luck, amount of luck required goes down with skill in pvp games) The point you raise about the matchmaking working against you doesn’t really hold weight because you done know the mmr of you’re allies in fact they might be high mmr or even high tier saph and hence the matchmaking.
Furthermore your win was a stomp 500-149 then you have two close loses, this implies that you are either holding you team back as you are the common factor in the two successive games after the win, which were loses. After such a stomp one would expect you to face teams of higher calibre and all that screen shot suggest is you cant handle the heat.
One last point is that on your team you had mes guard and warrior, they had two Necros and a warrior (that one can see form screenshot). You are in sapphire which I would assume means you’re not mechanically skilled enough to play Mesmer (and be effective); guardian is outmatched by the Necros and warriors a bit of a lame duck, admittedly they had a warrior to but;
2N+W>bad M+G+W (well known formula :p)
therefore what ever you played in that game instantly handicapped your team (as it was full solo q) and you deserved the loss, maybe if you had rerolled you could have got the extra points to win. If rerolling couldn’t be achieved then I think the situation you find yourself in is apt, viz. you should be around sapphire tier level of skill.
