Final performance rating is determined by the outcome of a roundtable discussion where your coach has to present your case which does not necessarily reflects your true contribution, and very much depends on the willingness of your coach to fight for you - which more often than not they DONT, just to avoid additional scrutiny from management.
Very unprofessional setting where a quid pro quo relationship is explicitly encouraged by your coach/peers/senior management where feedbacks are traded to help in presenting their rating in the roundtable.