According to the former Test captain the Pakistani players have been playing non-stop cricket for last six months and could be facing fatigue.
"And the fact is that our players fitness levels are still not at par with that of some other teams so that is also affecting their performances," he told the media in Lahore.
He pointed out that after Pakistan went to England in June they have been non stop on the road.
"After returning from England after just three or four days we went to the UAE for the West Indies series and from there directly for the tours of New Zealand and Australia. To meet such a gruelling schedule our players need to work more on their fitness," he said.
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Inzamam said that they were plans to improve things in Pakistan cricket but this would require time.
"We need to be patient and we need time before everything is perfect," the former captain added.
He said the Pakistan Cricket Board was contemplating a series of matches for the Pakistan A team players in the country shortly so that the bench strength could be tested properly by the selectors.
"If he is fit he is the ODI captain. Muhammad Hafeez captained in the two ODIs because Azhar was not fit."
Inzamam said the ODI series with two matches remaining in Australia was still open.
"I just think our batsmen need to put behind the fear of defeat behind them and play freely and aggressively. They are not expressing themselves properly and that is hurting their performances."
The chief selector said Pakistan needed to look at the way other teams were not approaching the ODI format.