I didn’t realize that player agents communicate with field managers. Here’s Jeff Banister on that relationship:
One thing I’ll tell you, being the manager of a team, that relationship with a player needs to stay one direction and that’s about playing the game of baseball. It is a relationship and a growing relationship. It’s not a contract relationship. That’s why you have a front office and a general manager and that’s why agents communicate with them. But there are a number of agents out there that I do talk to and there is an open line of communication with me about their players just because if there’s something going on that a player wants to talk to his agent about and they communicate that to me then I’m okay with that.”
That makes sense. An agent helps smooth out communications. A player might go an agent and rant and rave about a problem. The agent goes to the manager or the GM and explains the problem in a constructive way. Likewise, the manager or GM might rant and rave to the agent about the player, and the agent presents the problems to the player in a more positive light. This is why players and teams avoid arbitration hearings. The team talks the player down in front of the player, which is not pleasant for either side.