Black Adam was my first character in IJ1, actually my favorite DC Villain (I know he's more of an anti-hero sometimes).
But anyway, I do have to admit that I kinda hate that I'm falling back on him in Injustice 2, I'm learning Black Canary, Robin and Braniac on the side, but Black Adam is still my go to guy to clear stuff like Multiverse.
Though him being top 5, I don't know, he does a lot of damage, but he also has no lows, and even if you try to trick your opponent with an overhead into lightning strike, the lightning strike's startup is so obvious and slow it can be blocked on reaction.
He's also quite easily punishable, and his new string while having good spacing, starts with a high so you can just duck it.
He does well for me in online versus and ranked, but I don't think he has the tools to make it to the top where the pro's play as I feel there are better choices.
The only thing that really bothers me though is the lightning colour, kinda wish they kept it yellow, or perhaps like with GL have the shader he's wearing adjust the colour of his lightning.