In general for someone fresh out of college, Acads matter a lot. But you have to understand what do acads represent to the adcom at ISB/any other institution.
Acads are a way to showcase the fact that you are able to work hard and deliver results in a structured environment, consistently.
Given this perspective IF you are able to display the same trait through your extra curriculars ,mid-low academic scores should not be a hinderance.
Another reason for adcoms to consider your academic scores is to asses if you will be able to keep up with the rigorous and intellectually demanding course work at such schools. You can offset this through a good GMAT score (think 740 and above).
Essentially, look at your application as having different colored liquids, of different quantity in several beakers. (I am making up this analogy as I go).
You job is to mix and match every liquid in different beaker to come up with a color that Adcom likes. Trade-off, mix and match.
Think of larger questions:
Why MBA? Why Now? For eg
You could wait for another 3 years, get a sense of what exactly will a B-school give you once you pass out instead of applying right away?
Have good answers for these things and lower academic scores should get nullified. All the best.
Posted from my mobile device