Edwards Management Consultants interview questions

After phone and personal interviews I received the offer letter to sign from EMC as well as a promise to send me forms to fill later that day. After I signed and sent back the offer letter, instead of promised forms to fill, I received an e-mail the next day asking me NOT to submit my resignation letter yet because there will be another phone interview. Is it not a very strange hiring process? In a couple of days I had a phone interview and after that I was rejected because company is looking for someone with stronger experience in a certain field. I had a phone interview in the beginning and then an in-person interview with seven team members and Government Program Manager before getting a job offer. Is it not enough to evaluate my competence? If my competence was not satisfactory why send me an offer letter and ask me to sign it which I did?