"Tidied up massively" means I tidied it up massively.  Pretty simple really.  Whatever problem you have with the use of "grand slam" to refer to a single tournament is your problem, not mine.  Once you've convinced the world of sports journalism that they are getting it wrong, then you can change it here.  Until then, the article reflects the usage.  A simple question for you - is the title of this article "major tennis tournament" or is it "grand slam"? 190.44.158.38