Manager has all the power. Managers' relations with HR partner make it difficult to raise voice against biases. When HR is not neutral, you don't have many options left to continue your fight for right.
HR personnels are useless and are good only to perform admin works like shortlisting candidates for interview, processing payroll, formulating strategies, etc.
A lot of politics goes in the team, and the manager's favourite always wins, whatsoever his/her performance is.
Internal Job transfers are the worst thing to opt for as your career graph starts from zero every time you join a new time. Hence the overall growth slows down. Though HR conducts drives encouraging employees to apply for IJPs who have served more than 3 years in a team.
Your payroll and bonus is not co-related to your performance appraisal. So even if the onshore function has given a good pool of bonus allocation, the local manager blocks most of it and releases very little to the team. I have heard telephonic conversations as a concrete proof.