Related: Isaiah Bradley Exposes The Racial Hypocrisy Of Two (Captain) Americas

There have been numerous attempts to recreate the Super-Soldier Serum in the MCU and most of the results have been negative, from Johann Schmidt/The Red Skull (Hugo Weaving) to the U.S. Agent John Walker (Wyatt Russell). Steve Rogers was the shining example of the Super-Soldier Serum not just working but exceeding expectations. The reasons why were summed up by Dr. Erskine to Rogers: "The serum amplifies everything that is inside. So, good becomes great. Bad becomes worse." It was a simple fact that Steve Rogers possessed an ineffable positivity - simply put, he was "a good man" - that caused the serum to work so well on the original Captain America. Even Baron Zemo (Daniel Brühl), who loathes super-soldiers, itted that "There has never been another Steve Rogers." However, Isaiah Bradley may have been the second Steve Rogers based on how well the serum apparently worked for him.

Assuming that Isaiah Bradley's Super-Soldier Serum was as potent as Erskine's formula was for Steve Rogers, the issue with why others became unstable or died possibly lies with the other test subjects. Erskine disqualified many potentials for the serum based on their negative personality traits after he saw how his drug amplified the worst qualities of the Red Skull. It's doubtful that the U.S. used a thorough recruitment procedure when it picked a number of Black men to test their new serum on, and they likely based their choices on physical qualities. But the psychological and emotional makeup of the Super-Soldier Serum's recipients has proven to be incredibly crucial to its success.

A similar result was seen in Isaiah Bradley is that, like Steve Rogers, he is simply a good man. Tragically, as The Falcon and the Winter Soldier revealed, Isaiah was cruelly and unfairly punished for it.