What i see in S5, i am silver , is that matchmaking seems to me not so bad. The real problem is , quite often , auto team composition .
When you have a team at low level with 2 necro, 1 mesmer ,1 thief against 2 dh and 2 warriors + something else it is really hard to win .
Probably at higher level this has less impact becouse a strong mesmer for example, can be a problem for everyone and also a strong thief .
I think what people find frustrating is not the mmr difference at lower level but the team composition sometime you get and at lower levels people is reluctant to switch quite often so sometimes, when you start the match , you already know that if your opponents are at your level it will be really hard to win . Probably the system should try in any case to evaluate class stacking if possible