Players decide themselves if they want a manager or not, no one is telling them to sign with one, it just lets them concentrate on footy and thats it. A player manager takes care of all the off field business, such as, taxation, legal side of things, finding homes for players whether it be to live in or as an investment property, as well as get them the best possible deal from clubs and sponsorships and promotions.
Smile in answer to your question, yes they are the more respected managers in the game and do have some high profile players to. There are also bad managers who have a bad reputation, that being Gavin Orr, he has done alot of things to get in the bad books of his clients, it is why SBW left him, he also signed a contract and forged fuifui moimoi's signature on a melbourne strom contract a few years back.