What you are asking is a pretty broad topic. Still, I would try to explain why an Asian IT professional with 700+ GMAT score can get rejected by top B-Schools.
First , 700+ GMAT Score is part of your application package , the other parts being your GPA, application essays, work- experience and recommendation letters. Secondly, B-schools are not only looking for analytical skills in their potential MBA students, but also for leadership and team working skills , problem- solving skills ,initiative and involvement in non-work activities which are essential to their success in business and management. The reason they require applicants to write application essays for them is because they want to evaluate them on these skills.
While working with IT professionals on their application essays , I have observed that applicants with remarkable professional accomplishments shy away from sharing those accomplishment stories in their essays. Thus, one major reason why IT professionals with 700 + GMAT score can be rejected by the top B-schools is their inability to showcase their profile in their admission essays which play a critical role in the admission process. In fact, I find it hard to believe when some applicants with excellent profiles ask me ,"Do you think my profile is good enough for top-tier B-schools?" And they can't believe me when I tell them, "It is excellent. You only need to reflect on your experiences/ examples to illustrate your high potential." My experience shows that some IT professionals need to work in this area, and instead of writing essays that read like newspaper articles or extended resumes , they should directly answer the question prompt by illustrating it with stories/ examples from their personal and professional life.
In addition, they should make sure that their recommendation letters echo the same theme that runs through their essays. It is going to be a killer if your recommender says different things about you than what you are claiming in your essays.
I hope it helped.
MyEssayReview - A personalized and dedicated essay-review service