On flat pitches both batsmen are dangerous and Rohit is miles ahead of everyone when batting on flat pitch as he has a habit of gets going and 3 double 100s confirms that so its obvious that India missed him badly at the top order. I really hope that he comes back and he should take his fitness more seriously and eat less vada pav. 
That is applicable for the other players as well. Rohit is not the only player who gained lots of weight during the pandemic period. Even youngsters such as Shreyas Iyer and Rishabh Pant seems to have gained at least 5-10 kg during this period. Rohit is in his 30s and therefore his "gains" are more visible. On the other hand, look at the Australian players. All of them look 100% fit.
The difference may be due to the fact that CA is conducting domestic cricket this year, while the BCCI doesn't have a plan for the same. Especially for those Indian players who are not a part of the IPL, staying fit is quite challenging due to the lack of opportunities in domestic cricket.
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. I was expecting India to post a huge total when they won the toss but they failed to do that but to build the score from 5 for 152 runs to reach 302 runs is a huge achievement.