#1 A passing of the torch between two popular dark characters
The Undertaker has had one of the best careers in the history of the business, but we all know that his best years are behind him. He may not be done by a long shot, but we know that he's closer to the end of his career than the start and may only have a few years, at best, left in him.
Someone has to take on the mantle of a popular supernatural-ish babyface from The Undertaker and who is the better pick for such a role than Aleister Black, I ask? I mean he has a great entrance, he is a fantastic striker and he has many good years left.
I mean one can always make a case for The Fiend, but quite honestly, I would say that his gimmick is a lot more layered than The Undertaker and hence, Black is a better candidate. Sure, Black is a much smaller man, but in 2020, most men in professional wrestling are smaller.
And let's be honest for a minute. It's a good thing that he's not helping out WWE SmackDown characters and diluting the brand split.