Most of the job is based on the luck of the project/client/team you are on, and not how good you are at your job. Many people are consistently let go from the same teams. Managers will never let luck be an excuse so they will find anything to tell you that you did something drastically different when having a bad month versus a good month. Performance is also marked monthly, which does not allow for the ebb and flow of the business to be accounted for.