Why many IITians fail to cope with the curriculum after clearing entrance?

I am writing this article in response to the article published in Economic Times with the same heading.

The writer here seems to be only touching the things superficially and not working hard enough to first find what really is the issue and what are the causes? 

The  parts I fully agree with in the article are

"With the number of IITs going up and the old IITs expanding more seats, there is a huge gap in the merit of the top students compared to the students at the bottom," said Anurag Sharma, dean of academics at IIT-Delhi. 
"There are many such students who have entered the IITs with zero interest in engineering" said IIT-Gandhinagar director Sudhir Jain. 

Reason#1

RESERVATION

I think most of you will agree that this is the most important cause for such outcomes.

Firstly IITs should release the data about how many of the expelled students were from reserved categories. With the implementation of OBC reservation, government increased the seats in order to have same number of general seats as before and in a very hasty manner increased the burden on the institutes which I don't think they were ready to take.In this drama of OBC and General its the SC and ST candidates whose number increased magically . This magical increase is what has led to the present problem. Its not only the problem of quality of students but the undue burden on institutes because of increased number of seats is also hurting everyone.

Reason#2

Deterioration IN PRIMARY AND SECONDARY EDUCATION STANDARDS

With the decline is shine on Govt. Schools a lot of Private public schools have mushroomed all over the country which don't have the honest(note the word) and even proper qualified teachers. As a result greater number of small coaching institutes or tuition teachers have also come up at the I-X class level who are promoting the rote learning as majority of them themselves even don't know the concepts really. Plus the books have changed but the teachers were not trained to teach on the lines and this mismatch is also hurting.

I again sincerely appeal to all of you that please don't single out IIT Coaching Institutes as 100% responsible for all the debacles. I agree that many of IIT coaching institutes are actually not helping students to actually learn and enjoy the Science and Mathematics but some are doing it very well.