Worth it: Virgil van Dijk has justified his £75 million price tag at Liverpool. (Photo: AFP/Oli Scarff) Jurgen Klopp, who persuaded Liverpool to spend a world-record fee for a defender by completing the £75 million signing of Virgil van Dijk from Southampton last January, might beg to differ with Ferguson’s long-held view but generally, the biggest and best-run clubs avoid the January market at all costs. Van Dijk has been a huge success for Liverpool during his 12 months at Anfield and is, perhaps, the exception to the rule that states the January window is dominated by panic buying and expensive mistakes. Having banked the £75 million for Van Dijk, Southampton invested £19.1 million of their windfall on Argentine forward Guido Carrillo from Monaco. After just five Premier League appearances and no goals for the Saints, he was shipped out on loan to Leganes as a costly flop. Carrillo is an example of why Ferguson, and many big clubs and leading managers, have been so reluctant to sign players in January. The biggest clubs now spend months working on prospective signings, scouting them and diving deep into their backgrounds off the pitch. Sometimes, circumstances dictate that they have to do…