I like Christian M'Pumbu. Let me get that off my chest. He is a very good fighter, with a killer instinct and devastating power.
That being said, he needs to develop his game.
He lost a non-title fight to Travis Wiuff recently that in any other promotion would not have been a non-title fight, meaning he would have lost his belt.
M'Pumbu is a talented, athletic fighter. He needs to continue to work hard on his game that, if properly managed by a reputable trainer, could bring him great success.
How he'd fare
Sadly, M'Pumbu would be in the lowest ranks of the light heavyweight division. There are too many well-rounded, extremely skilled light heavyweights that would destroy M'Pumbu. He could grab a fight night bonus or two, though.