Like all people coaches are people with emotions, fallacies, pressure, ect. - the same as anyone else.
I see parents "at work" on the coach all the time. I know that some of the players in our program are on the team for reasons other than skill.
I would classify that as "political" in the realm of baseball(or sports) - maybe "like" would be a better term.
I encourage my son to talk to his HS coaches all the time and develop a relationship with them. Fortunately, for him - he is good at this - not to take away anything from his skill because he is a good player.
It would be naive to think that how a coach "feels" about a certain player does not go into account when determining playing time, positions, ect.
I have coached youth sports for 17 seasons (football and baseball) - I try to be as fair as I can but personalities come into play - and I don't think that is a bad thing. Obviously, it can be an issue if there is blatant favortism - but as mentioned above - if players are somewhat equal in skill - then "politics" will play a part.