Barcelona's woes are entirely technical. These are not issues you solve at a snap, and I see chances opening up for other Spanish teams to make a title charge.
Indeed Barcelona still relies on Messi et al but it is difficult if the coach does not carry out a good strategy, for example last night Barcelona was unable to win against Slavia Prague at home even though there are many opportunities for Barcelona, so I still doubt whether Barca is still coach by Valverde.
Relying on just one player and not having a second plan when this player is missing the first line up is what it makes Barcelona do weak.
And also, they are going to have bigger problems when Messi retires or leaves the club.