Well, I don't think that 157 was a good score to defend when your opponent have got players like Rohit Sharma. Everybody knows what he can do. So I believe Delhi Capitals needed more than 170 runs.. may be 180 to defend against strong team Like Mumbai Indians. Everybody expected much tougher competition in the finals, but that wasn't the case. MI easily won the match and lift the title for the 5th time.
After 15 overs, DC was comfortably placed at 118/4. Usually teams get 70 to 80 runs from the last 5 overs, and based on that I was expecting a total of somewhere around 190-200. But they failed to even score 10 runs per over at this stage (they could manage only 36 runs from the last 5 overs). This is the sole reason why they lost the match. Another 20-25 runs could have made a huge difference.
You are correct, as MI bowled well to restrict them to just 36 runs in last 5 overs where they had still 6 wickets left. This would have given some relief as the chase was under 8 an over and the way Rohit started his innings seemed he was set for the target to chase easily and it happened the same. But overall was a good match but not really a tough final that would have expected.