To be fair, the criteria do differ from office to office and program to program. 

Typically, no, the GPA would not be a make it or break it criteria and some offices don't even look at it specifically. 

But I do know that there are certain countries and offices where the GPA means a lot and that they use it as the core way of differentiating candidates. 

The reality is that you can't do anything about your GPA at this point. And not applying is like not even getting a shot at it. 

So I'd recommend that you apply not only to McK but also to other firms that run similar programs. And that you develop an absolutely awesome application to ensure the probability of passing is high. 

Here's a guide you might find helpful on how to do that:

• Expert Guide: Build A Winning Application Strategy

Best,
Cristian