Deloitte Business Technology Analyst interview questions

The first 2 interviews were on-campus(1 behavioral+1 case).They went well and was called on-site 2 weeks later. The weird part was all the guys from the 1st round got calls on-site. The on-site interview(1 interview comprising of behavioral+case) was a complete eyewash.The interview went well(with the interviewer appreciating my answers).However,the interviewer didn't seem interested(there were no notes being taken as in the 1st round) and it seemed as though the interviewer wanted to get over it asap.It seemed to me as if they had made their decision before hand. The interviewer said best of luck to me after the interview which gave me the signal that they aren't going to hire me. I got a reject by e-mail a week later.I had no idea what went wrong!