Im currently Allstar 4 and this is only my opinion but I have personally felt that these chars just dont have strong enough builds in my opinion to be worth playing they can still be played well but often times just seems so much more difficult.
Tank: JQ - I personally thought she would would be better but the trick is to just force her shout out fast and then burst her down and the rest of the team somewhat crumbles
DPS: genji - This one is really surprising to me but he just tends to be shreded a lot and I dont think ive seen many in my rank
SUPP: Zen -without a doubt its him he can do decent amount but he has to be protected so much and stadium is just a clusterfk of madness that he will just get dove and taken out fast
Now i dont know exactly how these chars could be played better but truthfully once you hit allstar I dont think you can easily secure a win when playing these chars simply just because of how easily each one can be shreded after pinged and removed. Feel free tho to correct me if you feel like im wrong im in allstar 4 atm so its not legend and maybe at legend these picks seem to dominate more. So what are your guys thoughts on chars that you feel need the most help. Also im a lucio main in stadium so perhaps its because I play him mostly that these chars seem to struggle the most.