In addition to his menacing role as Negan’s right-hand man Simon on The Walking Dead (for which he was recently promoted to series regular), most fans likely know Ogg for his work as Trevor Phillips in Grand Theft Auto V. In that particular role, Ogg plays Phillips as a man completely unhinged; a guy who lives for violence and can explode in a burst of oddly charming insanity in the blink of an eye.
Those are qualities that we look for in a Joker, and it looks like Ogg seems to think that he could pull it off if granted the opportunity.
Bringing Steven Ogg in as Mr. J feels like one of those casting decisions that arguably makes perfect sense, even if you didn’t immediately think of it.