Johnson too big and strong. Don’t forget that during his first career Mugabi fought Light Middleweight and Middleweight. Not even Super Middleweight. No catch weight fight here. A 154/160 vs 175 world class. Mugabi loses badly. Too small.
This is a mismatch Johnson would destroy him within 3 rounds, you're talking about a very good Light Heavyweight vs a solid Jr Middleweight/Middleweight. Even Marvin Hagler as much as i respect him knew it was wise not to move up to Light Heavyweight during that era.
I think Johnson’s just too big. I know that’s a tired old phrase but when you have two huge punchers and neither terrific in the defense or chin department the bigger guy is going to have a huge edge