If Barcelona were a strong team like before, we could say that Real Madrid would not be the champion so easily. Barcelona are not really in a good shape at the moment, they have not been a serious contender in La Liga.
But we need to point out that Real Madrid also plays really high quality football. We wouldn't be wrong if we said they are the best team in the world right now. That's why we can say that the team does not have many shortcomings even after Benzema

Don't say Barcelona weren't serious in Laliga, Xavi put all his life with Barcelona and was doing everything for the team to win but what did he get in return, backlash and crazy fans were not satisfied as if other people that manage the club did it on there own. Everything Barcelona has achieved today is from the glory of Messi and that's why since he left the club, it has been difficult for them to lift the Champions League, I'm not sure if they are going to do that soon.
Messi was not the only source of Barcelona past success rather the last inform players from the likes of Xavi, Iniesta and others while the older ones were a shadow of themselves. Without Messi Barcelona would still be doing well almost like Real Madrid if they were not facing financial struggles, don't forget Barcelona was still not really doing well in the UEFA Champion League before Messi left.
Aside from Xavi personality, i guessed his pride which made him have issues with some players and I guessed with the board and some fan, i think he did well except outside the domestic leagues competitions where he didn't do well though this season performance in UEFA Champion League was better for them, he was unfortunate from the fact that there were not enough players for him to rest key players who then became injured and they have to suffer from it.
Real Madrid remain Real Madrid, there has not been a lot of modifications of players in Real Madrid except for the departure of Benzema and they were affected for 1 seasons, cooking of midfielders elevated them back to where they are today but Barcelona sold many teams and bought garbages and they expect Xavi to use that to win the Champions League, like who does that? Since they think Xavi is the problem, let's see how far they I go in the next season.
Xavi chooses he wanted to buy though still limited by the club financial struggles but they tried to get the key players he wanted who love the club and wasn't bother about payout rather putting on the Barcelona shirt.
The main reason he didn't really do well last season was because the team players were exhausted after continuously playing throughout the past seasons and also in their national team, Barcelona suffered the ultimate punishment from it this season but if the same occurs this season they may even do worst because even if they try to do well this season, Real Madrid will likely be above them because they're not sleeping strengthening an already fearsome squad.