United was busy during the August transfer window as they were able to bring in Jadon Sancho, Raphael Varane, and Cristiano Ronaldo.
Reports revealed that United could have added highly-rated defender, Koulibaly, from Napoli last summer but they could not agree to Napoli's sales price of £34.1M.
They would later go ahead to sign Raphael Varane, who was 2 years younger than the Senegal international, and it would have been close to impossible for the Red Devils to bring in Koulibaly after signing Varane.
For the record, Koulibaly is highly regarded as one of the best centre-back in the world, some rate him closely behind Virgil Van Dijk.
