Abathur is VERY popular in QM. To the point that it is annoying.
To me, it feels that every time he goes symbiote build, and has a normal bruiser in his team - like Sonya, Artanis, Varian, etc. the game, and especially late game starts to be about only one thing - trying to kill this bruiser. He can survive almost everything, and in QM you mostly do not have the necessary CC to lock him down.
On the other hand, if he goes different build, Abathur feels like a dead weight that just annoys people with his Toxic Nests, or Locusts, which do not have a big impact.
To show some background for my claim heroesprofile has following win rates (QM, this patch, hero level > 10 - to filter out people that are just trying the hero):
Symbiote build 55%
Locusts 46%
Toxic Nests 43%
I am not sure what happened in the past, but I would like to have this more ballanced, I do not like to play against one unkillable hero, as well as I do not like to play with Abathur that just spams Toxic Nests or Locusts knowing that it does not do much, and yes, I've seen videos how he baits people into bushes full of Toxic Nests.
