To me he is mid+ but he is also the hardest character to play in term of execution (not metagame) which makes him even harder (don't get stress/delay in tournament with dat char lol).
He has one of the best string in the game : 21122 (the first hit is high and won't connect after a bf3 ex because you can duck), which won't make him shit tier, but if you know the matchup, Erron Black isn't that good, especially after the multi-nerf patch. The character has always been overated because of Sonicfox, but I don't know if we are going to see the cowboy being top 8 that much from now. Outlaw may be still pretty good with the OS.
I main him for the very beginning now, I have some secondary (Tanya, Kotal, Kenshi, Torr, Goro, Shinnok, Dvorah) that I play time to time and I feel like my Erron Black is one of the weakiest of my cast (It was weird to me as well) once people figured out the mu.
Offline you can armor him in reaction on the overhead (f1). I really think this character is overated. His d3 command grab doesn't connect anymore (I believed Erron Black was a grabber...), his pokes have a very short range, his backdash is awfull, his command grab is now useless in BnB, his zoning is limited (bf3) in most matchups, in Outlaw he had a particular neutral jump punch due to his variation but NRS nerfed it while Kung Jin, Quanchi and Raiden still got theirs in an universal way.
Gunslinger could answer to bad matchups but it's not even viable without changes patch by now.
When all the other shit char will be buff (and they will), I think Erron Black will have hard(er) time. I may be wrong but this is how I feel it. I see everyone dropping him, and despite Sonicfox (who's pretty skilled), I haven't seen him shined that much in tournament.
However, Erron Black stays the funniest char to play in the game.
@xGunShow @HeroesNZ did you drop him ? What do you think ?