Consistency will come with more experience. Look at the players. Yashasvi Jaiswal is just 22 years old. Shubman Gill is 24. Even Shreyas Iyer is still in his 20s. Rishabh Pant would be a good addition to the squad as well, and he is in his mid 20s. And then we have all the younger players who are still in bench, such as Sarfaraz Khan (26 years old) and Abhimanyu Easwaran (28 years). These players can only improve with time. Even the second string keepers, including Anuj Rawat, Jitesh Sharma and Dhruv Jurel are all in their early 20s.
Yashasvi Jaiswal spot in test cricket is reserved because of his two double centuries in two consecutive test matches. I am not sure about Shubman Gill, he has already played 23 test matches and he is not very consistent in batting. He has scored 91 runs in last test which means he has secured his spot for this series at least.
It was England second biggest defeat in terms of runs and heaviest in 90 years. England should have scored at least 250 runs in second innings to avoid such humiliation.