In an article on ESPNSTAR's cricket page, Harsha Bhogle had also made a statement about Zaheer's fitness.

From Harsha Bhogle's article
Easier than these (the earlier part was about the Abhijit Kale incident), but more immediately relevant, is the question of Zaheer Khan's hamstring. On the ESPN cricket show I spoke to Javagal Srinath last week and he was convinced that Zaheer was still India's number one bowler. There is much merit in that statement because India needs a big hearted bowler, even to bowl the old ball against Australia this year. His hamstring has now let him down thrice this year and that means there is either a chronic injury or he is returning to cricket too quickly. Hopefully Zaheer's early return is just a precaution but it cannot please his captain who has so much faith in him


It is a very long time since India has fielded a full strength bowling side in a test match. Against Australia this October India must allow themselves the opportunity of picking Zaheer and Pathan, Harbhajan and Kumble. Anything less than that will be, to return to the theme of this article, sub-optimal (another Kale incident reference).
Very valid points. His fitness is a major issue, and has affected his bowling form, and probably his batting and fielding as well. I do agree that Zaheer is the team's premier fast bowler, but if he keeps gettig injured and smacked all over the park so often, it will have the Indian team in trouble quickly. Hopefully Gregory King will have a solution.

Indeed, it is good to have a big hearted bowler, but time and again, it has hit the Indian team hard, as in the World Cup final, and several matches against the Aussies and even one against Pakistan. Sometimes, it pays to use a little intelligence and a lot of focus. This got Zaheer his 3 5-wicket hauls in Tests and should get him a lot more. However, his bowling in the second innings is far from encouraging and needs improvement.

Much as the Indians have to field a full strength bowling attack against the Australians, if aheer is brought in a little too early, he may break down again and it is as good as having a bowler less. The question is- whether to keep him in regular action till the series or rest him. He has to be in action to be ready for a big event, but he should not break down again. If he was 100% fit, he would have been one of the best fast bowlers in international cricket (although lack of pace may be a weakness, as in Mohali) and a better batsman and fielder. Indeed, an issue which needs careful planning and decision making. The team cannot afford to have Agarkar or some rookie leading the attack for long, so the sooner Zaheer and Nehra return to full fitness and form, the better.