There are a lot of issues at play in this documentary - but the focus is squarely on getting paid and the stakes involved as each player is scrutinized with regards to their abilities as well as their ages / identities.
It is strongly implied, no matter how great the potential - Major League Baseball will dick around and do what it takes to keep bonuses paid out to Dominican players from getting out of control since it's been that way since the first group of players were signed.
Still, young Dominican players each year have big, confident dreams as they are cultivated and showcased for MLB teams by trainers - whose livelihood depend getting a cut of the bonus they expect their players to get.
MLB teams are looking for the youngest players possible [16 is when players can officially sign with a MLB teams] - so players lie about their ages to appear heads and shoulders other players while supposedly still having potential to grow.
In response, if a MLB team is going to pay a player - they are going to make sure that the player isn't lying about his age and/or his identity.
Sano, who looks like he is on the way to the major leagues [despite not playing in 2014 due to injury], was the top international talent in the Dominican back in 2009 - but his family felt a prominent Pittsburgh Pirates scout [Rene Gayo] had a role in holding up the MLB investigation of his identity / age, so there was no bidding war and Gayo was essentially blackmailing the family to sign with the Pirates.
In the end, Sano signed a $3.15 million bonus with the Minnesota Twins - the movie shows his entire family's frustrations when they weren't sure things were ever going to get resolved.
While the doubt over Sano's age might have derailed the start of his pro career, there was no doubt he was a prodigious talent - but for Batista, the other pelotero, things got worse.
Instead of being considered a top talent, Batista got less money and became just another guy - his story maybe actually be more interesting, since we see the relationship with his trainer [Astin Jacobo Jr.] got worse.
When Jacobo Jr. finds out Batista and his mother lied about his age, it knocks the wind out of him - Jacobo Jr. felt betrayed and has some harsh words, because he put so much time into taking Batista under his wing, only to have his reputation smeared when the truth was found out.
Batista, who seemed determined and confident at the beginning of the documentary, looked deflated - he signed with the Houston Astros, but not for the millions he was anticipating to get from some MLB team.
Because Batista was found to be a year older, it meant he was suspended by MLB for a year - his last professional season in the Astros' system was in 2013 and after playing in the independent leagues this past year, is looking for another opportunity in affiliated baseball.