I thought that Quick Match would try to match you against another team with a similar composition. For example, if one team gets [1 support + 1 warrior + 3 assassins] the other team would also get such a composition.
However, in one of his videos, MFPallytime mentions that the reworked Tyrande (still Support) will be matched against another "sustain" heroes, which could even mean he'd be "mirrored" in the other team by an Abathur (a Specialist), or a Medivh (also a Specialist).
My own recent experience seems to support the hypothesis that there is such a different, more fine-grained grouping of heroes that is used to create "mirror-ish" matchups in Quick Match.
Is this correct, and if so: what are the hidden groups and what heroes do they contain?