This might be a stupid question but, what is a field assistant?

If your saying a guy has a field assistant, then its a wingman. Just another name for it like point guard, or crew chief. He basically makes sure no other guy tries to move in while his friend is trying to hook up with you. Also he's the one that (and this may sound bad but its the way it goes) talks to your less attractive friends that may want to block his friend from talking to you mostly cause their jealous or just lesbians. It's kinda like chess he's a knight or bishop that tries to block pawns from getting to his friends queen.