Can someone please explain the ranked changes for this patch?

So I know all the changes that they made for the ranked system such as Gold 4 being the lowest tier, and the fact they added new tiers, but my question is I was at Gold 5 89 LP before the patch and started today at Gold 4 with 0 LP. Lost one game and now I am Silver 1 with 89 LP. It really makes no sense that 1 game should determine whether or not I dropped a whole division of rank considering up until this loss I was on a 4 game winning streak...can someone explain the logic here please?