If you have no idea about players or never follow test cricket in general even scorecard then stop making general comment. By making such comment, which has virtually no facts and far from reality, you're not adding anything in discussion and it might look like spam.
In last 3-4 years India did nothing in their middle order, in 99% matches Kohli-Rahane-Pujara. Only couple of match i remember when this trio didn't appear together was cause of injury issue or break. That's it. So no they didn't do any experiment with the middle order yet. Now they are moving on which is a good thing.
Don't forget India won 2 back to back series in Australia and atm leading series by 2-1 in England. They won everywhere except South Africa and NZ. Not to mention virtually undefeated at home, they lost only 2-3 series in last 20-22 years at home.
Indian Chief selector said that he requested all dropped players to play "Ranji Trophy" so that selectors can review there performance and fitness. This idicates the fact that Rehana and Pujara are dropped because of there decline in performance. Ajinkya Rahane has performed well in match between Mumbai and Saurashtra, he scored 129 and 91 in two innings while his team lost the game. While Pujara was out on duck but still his team won.
https://www.espncricinfo.com/series/ranji-trophy-2021-22-1280196/mumbai-vs-saurashtra-elite-group-d-1280414/full-scorecard