Flex Queue Placements Question

@Riot

So I'm really curious about how you're determining flex queue ranking after placements. I was P2 in pre-season when it ended (placed in P5, ranked up to P2 before it reset) and have been a diamond player for the last couple years. Post-reset I did my placements and got placed in P4 which was higher than I expected considering I only went 7-3 in placements. I was expecting high gold.

Meanwhile my buddy who was P3 in pre-season in flex went 6-4 and got placed in G4.

I thought that was strange.

But then this happened. My other friend today who was P5 in pre-season after losing a string of games before reset went 3-7 in placements. He just got placed in P2.

To put that into perspective, he's only been above P2 once in his entire league career in any queue. He also managed to climb three divisions from his highest pre-season rank despite a 3-7 placement record. To top it off he was playing against gold and silvers in placements.

What is wrong with your placement system in flex queue?