3. Samuel Umtiti
Samuel Umtiti quickly established himself as Barcelona's first-choice center back during his debut LaLiga season. Bought in 2016, Umtiti has seen his market value skyrocket since becoming a Barcelona player. He further cemented his reputation as one of Europe's top defenders after helping France win the World Cup.
Unfortunately, he has endured a difficult time since he picked up a serious knee injury. He was even unable to start ahead of fellow countryman Clement Lenglet last season.
Some expected Umtiti to depart from Camp Nou, despite the former Lyon star signing a new long-term contract last year. However, Umtiti decided to stay, and his problem has now seemed to become worse.
The 24-year-old was sub-par for most of Barcelona's pre-season campaign. The Catalans struggled to contain Arsenal's attack before Valverde decided to replace the Frenchman. Umtiti was also arguably Barcelona's worst player against Napoli.
He got nutmegged a couple of times and looked like a shadow of his former self throughout the pre-season tour. Jean-Clair Todibo could possibly start ahead of Umtiti if he still fails to regain his form soon.