Would be very interesting, wonder what the possesion stat would be like... 2015 still had Busquets and Iniesta, would they be able to keep the ball for long? Both Suarez and Neymar had some error percentage as well, lost the ball more than Pedro or Villa. And would they be able to take the ball from the GOAT midfield, or would they be forced to sit back like every other team that faced 2011 Barcelona? If so, 2015 is not very suited for that, Valverdes Barcelona would do better then...
The 2015 team was obviously great,but the main cornerstone of that team was the MSN trio...the midfield was still pretty good,but not on par with peak Xavi-Iniesta-Busquets triade.I also think the defence was better in 2011 too.it would be a very interesting match surely,and for me those teams are the best teams in the last decade alongside Bayern Munchen cca 2013(yes,all of them better than the third time Real Madrid champions-their peak level wasn't as impressive as those three teams and the competition was weaker),but i still think that team was the pinnacle of football.Opponents of high quality like Mou's Real Madrid were scared to death before encountering that team.
P.S.Pity we just live from memories.2015 seems such a long time ago...hopefully,we'll start being the team that is always feared in the future again.