Sanchez has some alarming stats, 4th most dispossessed player in Europes top leagues, 1st in most inaccurate passes
Comparing them both you may have missed what Pep thinks is most important going off premiership stats Sanchez 19 goals 9 assists Aguero
18 goals 1 assist even off other comps there is not much if any difference except the FA cup.....
As far as Pep is concerned imho its what a player brings to the team as a whole and off performance and stats alone Sanchez wins hands down.