But speaking to CNN, sports business expert Simon Chadwick questioned the relevance of measuring value in this way.

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"It's simply a very nice piece of short-term brand alignment that will be mutually beneficial to both parties, " sports business expert Simon Chadwick told CNN.

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"Rather than competing against one another, Sharapova and Na actually provide Eisenbud's business with much greater global coverage, " British sports business expert Simon Chadwick told CNN.

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"This is significant and fundamental because it is changing the very nature of sport: the formats, " Simon Chadwick, Professor of Sport Business Strategy and Marketing at Coventry University, told CNN.

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However, British sports business expert Simon Chadwick argues that these figures do not show the whole picture -- and he insists that brand value is more complex than mere numbers can portray.

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Where Shanghai and Guangzhou are concerned, the recruitment drive is being funded by wealthy individuals who, according to Simon Chadwick, professor of sport business strategy at England's Coventry University, see football as a way to gain political influence.

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"Ronaldo can be viewed in the same bracket as Beckham when it comes to global commercial impact, if their image is controlled right and Real Madrid improve their results in the UEFA Champions League as a result of their arrival, " said Professor Simon Chadwick, Director of the Center for the International Business of Sport (CIBS) at Coventry University in England.

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January's transfer window brought winger Simon Wiles and strikers Nick Chadwick and Luke Powell to the club.

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