4. Borja Mayoral
Borja Mayoral was developed in Real Madrid's youth system, and was gradually promoted up through the ranks until he eventually found his way into the Real Madrid first team set-up. He was given a chance to prove himself in the 2016/2017 season with a loan move to German side, Wolfsburg.
The Bundesliga is a very tough, competitive league with lots of great players, so there's no doubt that Madrid were keeping a close eye on how he performed. The 19-year-old featured in a total of 19 matches and scored twice, which isn't bad at all for a player finding his feet.
Upon returning next season, Mayoral was thrown into the mix at Madrid and featured in 14 games, where he netted three goals and even got himself an assist. These were promising signs from the youngster, but the fact of the matter is, how likely is it that Mayoral will ever get a reasonable amount of playtime at Madrid? If he wants to truly kickstart his career, then he needs to seek a move elsewhere.
Sevilla and Real Betis have been the two frontrunners for his signature this summer, and Marca.com even reported that Madrid had offered Mayoral to Sevilla, but their manager, Pablo Machin, is reportedly uninterested in the deal.
Will he stay or go? For the future of Mayoral's career, he should leave; as far as Real Madrid are concerned, they might keep him to sell him on for more at a later date, but he'd remain a player who's used sparingly.