It beats me. I cannot figure out why this is happening.
The popular feeling as well as the informed opinion seems to be that if India are to put up a strong show in the upcoming round(s) of the competition, MS Dhoni would be better off at No 5 or 6 and vacate the number three spot he has occupied 'by force' as it were.
This is a smart player and tactically agile captain - does he fail to see the point? Having led a middling Indian team to triumph in 2007, surely he knows that T20 is all about seizing moments quickly. While 20 overs is a long enough time, the model cannot be consolidate-build-explode. There is no time to have 'a look' at the bowling. (Do it from the dugout if possible). I am convinced that Dhoni knows his strengths and weaknesses as a batsman.
In fact I would venture to say that knowing his weaknesses only led him to what Harsha Bhogle calls "Dhoni Mark II". MSD, somewhere in September-October 2007 realised that the bowlers have figured him out and adopted this mode of play. Why, during the home ODI series defeat against Australia, MSD was outscored by Robin Uthappa in the sense that RU was able to get boundaries at will, with his Hayden like walk down the track, while Dhoni was not quite as effective slogging.
In the CB series, we saw him go into the accumulator mode for keeps. He has figured that works best for him. It also has helped that this team is full of more capable batsmen who are better equipped to get quick runs.
So it is not as if the captain who is so good at assessing, pitch, opposition, bowling attacks and passages of play has failed to get his own batting order optimised.
As I said before, it beats me...