BCG does not care about senior management. They are usually called in by activist investor(s). Sometimes it's a hedge fund with many shares with the backing of a few other big funds. Something it a letter to the SEC, sometimes not. They are there for one thing, increase the stock price. Short term, they are very good. They recommend to cut everything. Because of the massive cuts the stock will go up short term. The earnings per share go up because they cut people, good people leave because of the crappy culture, and all that is left is a shell of a company. Before the stock crumbles, the activist investors and big funds leave. They will stay if the company can be broken up or a M&A can happen. They are just corporate raiders.
Merck pays BCG tens of millions of dollars. They do this so they can keep the information. In most cases it gets leaked to the activist investors/hedge funds anyway. That's only nature because they force them into the company to begin with.
I have worked with BCG and they are a bunch of idiots with no real world experience. Then again they don't need it. They know why they are there. It's not to grow the company. They are too stupid for that. It's it increase the stock price. Big difference between the two.