Barcelona clearly have a mentality problem and there is lack of leadership in the dressing room. Not just Messi's fault, the likes of Alba spent halftime at Anfield crying for 15 minutes while they were still only 1-0 down. Pique should be the cool head at the back but he becomes passive instead and doesn't comunicate. The body language of the players when they're in trouble in a big tie has been appalling, it's like they're defeated even though it's all still to play for.
If they had a Puyol there that doesn't happen. They might lose anyway but never like that where the team just crumbles completely.
Pretending that this is all irrelevant and the mental aspect of football has no impact on the game is plain wrong. As is putting the blame for Barcelona's problems all on Messi. He's the captain but he's never been that kind of captain and they should have found someone with those characteristics after Puyol and Xavi left.
Xavi wasn't a "guts" captain, even in his last years the club was sunk in apathy (Roura and Martino seasons), and everyone in this thread seems to forget that the Roma fiasco happened with guys like Iniesta at the captaincy and Mascherano with his "cojones", his way of dealing with the NT situation post-netherlands in the 2014 WC wasn't the best for a captain either.
Thing is, this squad is depleted of emotion to overcome things, as we say in Spain they've already "done it all", from huge comebacks, to trebles, world cups, euros, leagues, copa runs... they just don't have in them the guts to throw a last hail Mary and fight a game to the end, when things go south you can read in Alba, Piqué or Busquets that "can't be happening to us, we're great, this is unfair" look, obviously Messi isn't going to be the one to bite their heads off, because it's neither his personality nor what the team needs from him.
We have a leech as president, non-respectable figures at the DoF sections (Pep Segura was there because of his connections, Robert wasn't some kind of commanding figure, and Abidal played with half of the roster but wasn't a leader), we have dull managers like Valverde (good at treating players, but lacked a spine) and Setien (who doesn't have the cache or the charisma to do a Luis Enrique and try to take the reins of the squad). Players get all of that, and the core that's been commanding our dressing room for years will remain complacent until someone unroots them from the club.
And regarding captancies, someone mentioned Ramos in this page, he gets a lot of praise because he's a charismatic guy in a team that has won 4 UCL titles but as captain material goes he's not top 5 in Spain, look at him "commanding" in the 2018 WC, leading by example... on how to screw up, or how he's got himself ejected in key games like vs Barcelona, the Ajax chapter, his desire to take penalties in the past when other strikers (like Benzema) could've used the moral boost of scoring. He's a primadonna, but he's not a better captain than, say, Navas, Koke, Joaquin, Soriano, Cazorla, Morales or Coke.
What we need is simple, we needed De Ligt to start phasing out Pique, we need to start saying goodbye to Busquets and build the team around FDJ as our DM, we needed a reliable striker to start eating Luis Suarez minutes and instead Suarez got Injured and we sold a forward, and we need a proper world class LB that can lock that wing up both in attack and defense. Not only are those positions key gameplay wise, they're also crucial in order to inject some new blood in the team.