I asked the same question a few years ago. Another poster mentioned that Larry Holmes commented on his brother needing to get off his ass and take on some real challengers. I guess he was a decent fighter with some ability, but not a world beater. He never showed that he could he step up and take on the big dogs.
The first meaningful opponent he fought, John Collins, he lost to.Maybe he should've fought Alex Ramos, or Doug DeWitt in a comeback bout, his career would've been different.
Good enough to be easily handling professional fighters in sparring while in his late 40s/early 50s. His main problem was dedication to the sport. He had the skills needed to go far, but didn't have the dedication to do it, which is why in the late 80s he found himself in jail for being a big time drug dealer.