At Boston, a sponsor, John Hancock, rather than the race organizer, handles recruitment of the elite field.
The other marathon majors use their sponsors' money for the same purpose, but do the recruiting themselves.
The different approach is even more notable because all the other ones have title sponsors, while the B.A.A. lets Hancock do this without being a title sponsor. The B.A.A. is left sort of like, "Why look who's running our race, isn't that nice?"
This seems wacky.