The worst heroes in Dota 2 patch 7.36b have been named

The worst hero Dota 2 after patch 7.36b was Sand King. Besides, Valve nerfed a number of popular heroes that often got picked in pro matches.
This is evidenced by statistics from the DotaBuff website.
Sand King slipped from the top rank and fell to the bottom in terms of win rate. He lost almost 12% since the release of patch 7.36b on this metric, however interestingly
Zeus who was so powerful and mostly picked by esports players during official games was also Nerfed too.
One thing worth mentioning was that many professional players welcomed this change as his ultimate ability which could kill enemies anywhere on the map was seen as overpowered.
Worst heroes of Patch 7.36b:
Sand King
Shadow Shaman
Nyx Assassin
Void Spirit
Zeus
It is also worth noting Axe nerf who came out as one of the strongest heroes last time due to his new aspect. The developers thought it was high time for them to balance meta and consequently highly buff not popular heroes that dramatically changed matchmaking win rates.
Recall that previously mentioned best heroes from patch 7.36b were given massive buffs before their performance in games changed completely because of these buffs