The prestigious IIMs invite students to interviews based on their CAT percentiles. However, the 99 percentile mentioned in the question is for General Candidates (i.e. the perceived influential social class in India). Male and engineer candidates are more likely to meet the 99 percentile.
The competition for General Engineer Male candidates is tough. Because of their academic and co-curricular achievements, the cream of the GEM typically receives the majority of the call letters. As a result, given the limited number of seats in top Business Schools, there is almost nothing left for a typical GEM.
The candidate in question, Vidit Garg, is not a GEM, nor an Engineer, and thus gleefully avoids the arduous competition that a GEM faces. He is also a candidate with professional experience, which gives him an advantage over freshers when it comes to managerial abilities.
To summarise, the only way a GEM can almost guarantee a seat in a prestigious B school is to excel on all fronts.
IIMA has a highly competitive admissions process based on a setlist of criteria. Apart from an academic performance one of the most important factors for admissions at IIMA is diversity. There is a huge demand for diversity amongst students from every batch at IIMA.
One of the biggest reasons why Vidit Garg received a call from IIMA was to fulfill one of the main criteria which is designed around student diversity.
Secondly, the admission cut-off and criteria are different based on the field of study. A breakdown of this difference and the 7 ‘AC’s’ are briefly mentioned below.
Based on the given divisions, the cut-off’s and requirements will be different across the given fields of study. For instance, the academic scores across class 10, 12, and graduation will be different for AC-4 and AC-7.
In that case, Vidit Garg was a BA student which put him under AC-2. This is likely to explain the low cut-off requirement.
Also, it is important to note that the competition amongst AC-2 must also have been comparatively lower. Furthermore, there may have been many other students who had a higher score in CAT but were not selected because of lower academic scores in Class 10, 12, and graduation collectively.
It is quite possible to get admissions at IIMA with 89 percentile depending on the field of study and the factors given above, making the admission process slightly uncertain. Hence admissions cannot always be guaranteed.