Keep Calm and Play On
Top/Support main here. So far this pre-season I've played a bunch of champs in these roles, some of which I haven't played in months, and have not lost a game in a few days. Even if my ADC feeds, even if Yas/Trynd are on the enemy team, even if someone on my team DC's or doesn't have new masteries, even if I play a mid/late game champion, we communicate and fight to our strengths. I've helped turn games we were behind in and played a 50+ minute game to victory after multiple 3/2 surrender votes on my team. Yes things are a bit unstable right now and some aspects of the game need tuning, but my experience these past few days has been very positive playing as tanks, bruisers, sustain and tanky supports, and dabbling in DPS champs too. I'm really enjoying playing different champs well and learning new build paths and vision changes.
TL;DR keep trying new things and play smart from behind, and more than anything encourage others even when they make mistakes. Even in this snowbally preseason you can make a comeback. Riot will make adjustments on initial over/undertuned changes. And you can use this time to improve your metagame skills a lot right now.