Born a Champion is actually a pseudo-documentary and Mickey Kelly's story is not real. Mickey Kelley is actually a fictional character based on Sean Patrick Flanery, the actor who played the role. Similar to Mickey Kelley, even the actor is talented in Brazillian jiu-jitsu. He has a black belt. The actor has been practising martial art since the age of nine. He even has his own martial arts academy where he teaches kids and adults.

In an interview with Screen Rant, the actor said that he wanted Mickey Kelly to look very authentic. Mickey Kelly is an old man who has been doing jiu-jitsu for a long time. Therefore, he wanted the character to look like it. As Flanery does jiu-jitsu regularly, he added he was able to bring that realness in the way he looked in the movie. He did not have to do anything special for it because he already has the said body shape.

With Flanery being passionate about jiu-jitsu, he referred to Born a Champion as 'true love letter to that martial art.' Flanery initially wrote Mickey Kelly's story on a UFC forum back in 2007, according to the portal. After deciding to make it into a movie, he made the post private. He later partnered with Alex Ranarivelo, the director of the movie, to co-write the script. The original story was also written in a documentary style, just like the movie.