Story writer probably didn't research enough about Mary Kom's real life. Its hard to imagine that the incidents shown in the movie were the ones that carry maximum impact.
Director was very average. Its hard to find useless scenes in a two hour movie. 2 minutes wasted on passport lost scene do not add anything to the movie. If the highest point of the movie is to show the struggle of a boxer post-pregnancy, why would you not show any belly fat or any scene contrasting her lesser power/ fitness etc. In fact, why would you not show a single scene of her workout before she got married. Nobody is born as a world champion.
Producer: Didn't fund enough to get decent actors... Though coach acted well, but this was perfect example of a very low budget movie.
And last but not the least: Priyanka Chopra... dude she was gonna casted as Mary Kom but she looked so delicate as if she is going to Miss World again. Completely misfit. A lady walks out after delivering twins without any visible fat. Hard to imagine especially when she claims women's body change a lot after pregnancy.