Soooo.....first placements, how are you doing? Any good news stories?

More than a little worried about doing my placement matches this season. Last year I thought I did badly, I played my 10 matches was new to ranked and in fact the first 3 games I was invited to and hadn't even realised they were ranked games xD Anyway I lost 7/10 games and placed at Siv my friend who I duo queued with played 5 games with me and he placed Sv. I was chuffed with my result as I had only been playing 2 months. Since then I have dropped a division that is over thankfully due to the reset. My friend who introduced me to league placed at Bi last year and has spent the year playing nothing but ranked and he finished the season at Sii. He was quietly confident about doing his placement matches and went ahead and won 6/10 of his matches....he placed back at Bi O.o His first 4 games were played in the new system and his final 6 back in the old one, but I don't get it. what chance do I have if someone who plays ranked all the time can't make an improvement on their placing a year on? I don't understand the mmr or win rate calculations so it is difficult to accurately assess what I need to do to place well. if it is down to K/D/A then in my understanding supports would be at a disadvantage since they take the most risks warding etc and are usually the last to leave the fight. More likely to die and don't take kills. We both main support, so rarely play together and never ranked. Although we played in the new system as a 3, one game. He has asked people and they say it is based on win rate but that can't be true as I lost 7/10 last year and placed better. Was the new system working correctly or was it broken? I could do with some advice because I am not going to play ranked I would rather stay lvl 30 than be bronze again. Can anyone tell me a positive story, that they placed higher than they thought they would? Is everyone placing a division lower?