I have really been looking at consulting careers, so far unsuccessfully I must admit, and I do not think MBB places H students at a higher pedestal than let's say NU students.
I think they have some bare requirements: high lsat score, high sat, top law school.
If you pass those requirements, you take their test. Their test is basic math, relatively easy I think for anyone that has scored over 700 on math sat.
If you pass the test, then you are interviewed two different times.
First time, you are interviewed at the office near your school. Here most applicants fail. Their interviews are tough, tougher than anything on OCI. Two interviewers, two types of questions each. First type of question is math/analytics/problem-solving oriented. It requires you to be fast, to know how to read graphs, to know how to ask questions, in a few words, it requires you to be smart in a consulting sense, not in a legal sense. I think a lot of law students, no matter their school or GPA do not do so well here. This is like the ideal place for people who like mental math, can think out of the box, can come up with a decent answer to a question like this "what do you think is the revenue from the parking meters in NYC?". They wonder here how you will approach the problem... how structured you are... how logical the steps and the assumptions you take are?
Personally, I love those type of questions, and also like logic games on the LSAT, you can train yourself to answer them.
The even harder part in my opinion is when they ask you about leadership skills, or about conflict management. If you have been in the military and investment banking, great... you will have good stories. But most of us, simply do not have much in relation to this. We had situations of silly conflict management, not real. Additionally, you cannot bullshit it... they grill you at it, grill you I say. They ask what did the other person respond, what did you think then, what did they do then... kind of like a deposition.
Additionally, even if you have good stories, they might not necessarily like what you say.
After this ordeal, yes that is how it felt to me, you are invited to an even tougher interview at the office where you will be working. Same format, I believe (did not make it this far), but partners thrown in the mix.
PS, to understand why they go through such lengths. Look at it from their perspective. Biglaw partners cover their associates because biglaw partners are the one dealing with the clients. As an associate you have time to prepare your info. and it goes first to partner. So as long as partner can live with you, you are good enough for the firm.
MBB guys are sent to their clients offices, on a small group. They want to make sure that if CEO passes by your office and asks you something, you will not sound like an idiot. Or if some department head is pissed off at you and your advice, you will know how to deal with it.