How does new placements work?

i recently took a dive in preseason and fell from b3 to 70lp in b5 and with the new season i figured i would make it out by playing well in placements and get back on my feet. Well with these new placements i have lost the lp i had in b5 and even fell back to the very bottom.

The first image is my preseason 5 stats then the last are after placements

so did riot nerf them so you literally get nothing from them? i tried my ass off and they set me to the lowest point i can be.