When Real Madrid bought Marco Asensio for €3.5 million last year, he wasn't as famous as he is today. Asensio was thought to be a great prospect, but he has proven himself as a quality player already with Spain in the U19 Euros. He's the leader of that team and he scored Spain's two goals during the win against France being an attacking midfielder. He's that good.
Knowing that Asensio would need minutes to properly develop as a player, Real Madrid plan to send him on loan after the pre-season. Real's roster isn't short of attacking players and Asensio would sit on the bench most games, something that would affect his development as a player.
More than 20 teams are interested in signing Asensio on loan this summer, according to ABC. However, he will likely join Espanyol after Real Madrid completed the deal for Kiko Casilla. Espanyol's President confirmed that they want Asensio and also that Real Madrid is willing to send him to play there. Betis are also interested, according to that same report.