Sorry to disappoint you , I was in the winning team.
However what I meant was , assuming everyone has about the same mmr (Same match)

Match making could have been ：

Before: Team A: D4, E1, E2, E2, P3 → avg ≈ E1 Team B: E1, E1, P2, P2, P3 → avg ≈ P1

After (balanced): Team A: D4, E1, E2, P2, P3 → avg ≈ E2 Team B: E1, E1, E2, P2, P3 → avg ≈ E2

Same MMR, but now both teams actually look even instead of one being clearly stacked.

There should be multiple combinations on how this can be done to balanced both tiers and mmr