#1 Lucas Digne
The French defender was bought by Barcelona for a considerable €16.5 million from PSG in 2016 after his impressive loan season at AS Roma. He had started nearly every matches for the Italian outfit and impressed in his debut season.
Barcelona expected Digne to be the future replacement for Jordi Alba as well as to provide some competition for the Spaniard at that time. However, the 25-year-old found himself frustrated with the lack of opportunities at Camp Nou as he started just 22 times over 2 La Liga seasons. Barcelona eventually sold him for a slightly higher price to Everton last year.
Now he perhaps has been a pain to watch for the Catalans due to his outstanding form with the Toffees. He has started nearly every match for the English side and has been involved in an impressive 7 Premier League goals so far.
The Blaugrana might still have excellent Alba at their disposal but Digne has been such a hit for Everton that he surely would give Barca some headache. He also has more room for improvements as he is 5 years younger than his Barca counterpart.