The Ashes has been quite back to back and both England and Australia have gone in with 4 bowlers and a batting all-rounder in Stokes and Green. If it is 5 bowlers, we should at a bare minimum go with a batting all-rounder instead of a bowling all-rounder like Thakur. Otherwise, it is just adding a bit more pressure to the top and middle order batsmen, especially when Pant is out of form as well.
India has a good crop of pace bowlers and I am not sure why 3 out of Bumrah, Shami, Ishant, Umesh, Siraj and Thakur cannot go at full throttle in each test with a good rotation plan built in. At least in this test series, a 7th batsman would have definitely helped India.
If Jadeja was playing, the current strategy would have helped since he is more of a batsman than bowler now. But there is no other batting all-rounder in the squad or vicinity currently. So, we should have gone with Vihari instead of any of the bowlers especially since he can bowl a bit too for the `rest` required by the pacers.
And I am saying that this should at least be a stop-gap option till we have 4 out of top 6 in imperious form and then we can probably think of going in with 5 bowlers. Right now, the batting is shambles and hence, needs the fail-safe more than the bowling.