You have to remember that most MMA films are from an alternate universe where the normal rules of film-making do not apply.
Most MMA films are nod-nod-wink-wink "vanity" projects done mainly so the producers and stars can spend the next few years bragging they "did a movie." Scripts, acting, direction, all usually terrible.
Every now and then you get a project like Warrior -- possibly the best MMA film ever done -- and you remember that it is indeed possible to do something that rises above the rest.
Philly Kid is no WARRIOR but a decent script, a decent star and the frenetic pacing of Sean Connery's son Jason (as director) keeps it moving along nicely.
In fact, whereas with most MMA efforts the challenge is listing all the reasons that it failed, with Philly the challenge is figuring out how it could have been even better? Chatham does a great job. He not only seems willing to tackle his next fight opponent, he seems willing to tackle a script that constantly has him playing catch-up. This a character who has literally no control whatsoever over his life until the final scenes of the movie.
I think that is the problem.
The intention was likely to setup a "story" problem and then reverse it (just like in a real fight) but by the time Chatham's character comes into his own, it is arguably too little too late.
And for that single reason, in the opinion of this reviewer, this solid effort never rises above the rank of wannabee.
But for the genre, it is not bad at all.