So India were bowled out under 150 runs under 40 overs. Australia have been doing this to teams in the first innings, but the Indian batting just was not up for it today... it can happen against the Aussies...
So when Australia came to bat, Dhoni started with Harbhajan- just to cut the pace, exploit the dry pitch and take early wickets to try to defend the low score. If India were to win or make Australia work hard, spinners were the key. So recognizing the given situation he had to make some execution changes. Perhaps a fair idea to start with Harbhajan (he could also have tried few overs of pace with keeper standing up and had they got a wicket, he could rotate the pacers. This way he could defer the spinners till 10 overs and power plays could be deferred as well).
However, as I have mentioned in my book, the key is to recognize the peculiar nature of any situation and try to adjust the execution accordingly. So what else should have been done or could have been done, to follow up the decision to start with Harbhajan (and Zaheer Khan from other end with pace). As some TV commentators pointed out, perhaps having more close-in fielders to add to the pressure, was perhaps required for wicket taking... perhaps, but it is not easy defending such a low score with many more fielders up close.
My major point was the line Harbhajan bowled
He bowled outside leg stump and over the wicket to both the left-handers (Gilchrist, Hayden). He was getting turn from ball one. This was a red dusty surface made for Indian spinners. He sure tested the batsmen frequently and got in many dots- as evident from his good economy rate. But when strike rate is not a major issue, will the outside leg-stump balls threaten the batsmen? (in usual ODIs it would be effective, since strike rate is of concern and balls from around the legs will have to be played at more often).
In my view, this is an instance of recognizing the peculiar imbalance of the situation (by Dhoni- low score, dry pitch, and the fact that Aussie openers can murder pace)- to convert to an execution issue (sending in a spinner). But the manner in which the spinner bowled (good turn, but outside leg stump line) was the chess equivalent of sharp positional play when a forcing tactical approach was required. Perhaps bowling round-the-wicket (since there was turn), and making the batsmen play a turning ball but pitched in line with leg/middle, could have been the line and then mixing it up with his variations of a doosra or even wide outside off...
Sharp Positional Play would be the answer if Australia were chasing 240 plus. Imbalance was recognized but the execution, in my view, should have been more drastic (tactical, with more risks if needed).
Not that Australia would have lost... but if you try something different, let the difference be as different as is demanded...
But the good news is that Dhoni looks like the captain who will keep trying, provided the rest of us let him...