the term "it is what it is" is an invention of Johan Cruyff

Mr Cruyff, who was born in 1947, probably just made a loan translation. See the late Mr Saffire's musings on what he calls tautophrases cites a usage of the phrase from two years after Johann's birth:
Quote:
The phrase, racing through the language, shows no sign of tiring. The first use I can find is in the Newspaper Archive, from a column by J.E. Lawrence in the Nebraska State Journal in 1949 about the way that pioneer life molded character: "New land is harsh, and vigorous, and sturdy. It scorns evidence of weakness. There is nothing of sham or hypocrisy in it. It is what it is, without apology." [link]
What about: "A rose is a rose is a rose" or "it out-Herods Herod"? As somebody, whose name I have forgotten andwho has the time to find out whom when posting on the Web, once said: "Have you ever noticed how clichéd Shakspear's language is? 90% or more of his more famous plays is tired and hackneyed and full of PC solecisms." [link]

Ceci n'est pas un seing.