I believe my demotion was unfair

Recently I was demoted at my job and feel it was unjust.

I started as a supervisor of a team which I hired. The job was call center insurance company. My team was statically the top team. I was asked to start taking calls and was by all indications via the key performance indicators one of the top representatives. Fast forward 2 weeks after that we are doing something completely different again by all of the scorecards that were going out company wide I was statisticly one of the top agents based upon the filters that were being used at the time.

I was demoted to lower than a representative later. The manager stated that they used different key performance indicators filtered in different ways to come to the decision. Furthermore I was told that they changed the key performance indicators for the previous role after the end of the previous job and I was not as good as other representatives due to the new filtering of the statistics. Furthermore since I was a member of leadership on the previous campaign they did not provide with the necessary amount of licenses to be successful in the previous role because I was not intended to take calls.

Now I have had my pay lowered and the people that I hired and brought in as representatives are now ahead of me making more. Do I have a case?