Ranked Team Provisionals

We made a ranked team consisting of gold 4, plat 4, plat 3, plat 5, and dia 4, and won all 5 provisional games and got placed in bronze 1. I am pretty sure our elo or the enemy team elo were not this low. I wrote a letter to riot games to help me understand this situation but didn't really help. I really think this wasn't a fair result. Can someone please explain me clearly about this? Thanks.
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