I wouldn't say Alena is anything like Xavi to be honest. I been watching him since age 14/15 and one of the points against him is he doesn't have enough "pausa" in his game like a traditional Barcelona midfielder.
Thats why, Puig looks like butter and Alena like margarine, because Puig is playing that Barcelona midfield style and slots in instantly despite his physical stature.
Pimienta had Alena playing more subdued for his B team last year and he was good, but when the games got stretched or Barcelona B was losing he would revert to his natural instincts. Vertical passes, vertical dribbles and long range shootings. A midfield wildcard. Like I said before, he has the style to build an attacking midfield around (think Fabien Ruiz) that a lower or midtable team would love to have.
Alena was/is a huge talent. But maybe his style in midfield is not going to get him alot of minutes right now as he will create alot of turnovers.
In Rijkaards days he would spot the talent of Alena and give him 25 minutes in AMR, 30 minutes in AML, 20 minutes in central midfield like Iniesta early days. Meanwhile Valverde struggles to even rotate an injured player.