In previous years(2008-2011), Barcelona were a dominant force that destroyed most teams. They had the tridents of Henry, Eto'o, Messi, and Pedro, Messi, Villa backed by Xavi at his peak with a brilliant Iniesta and Busquets. Behind them they had the great and fierce Puyol partnering the young and supremely talented Pique. The entire team was magnificent. Some players were only there for a bit(Yaya, Mascherano, Ibra, and various others) but the core of Valdes, Pique, Puyol, Alves, Busquets, Iniesta, Xavi, and Messi lead the way.
Since last season, it's been clear that the only players still playing at an incredibly high level that are fit are Messi and Iniesta. Xavi and Busquets have still played well but have dropped off in form a bit over the course of the seasons even though they've still had world class performances in some matches. Even Iniesta's brilliance isn't enough to overturn ties.
What I'm trying to say is that for me; Messi dragging Barcelona practically by himself over the past 2 seasons to a league win, a copa del rey, and 2 Champions Leauge semis with a squad composed of injured players(Villa, Abidal, Adriano at various points, etc.), aging players(Puyol and Xavi), and extremely out of form players(Pique and Alves at times) is almost even more impressive than the Champions League wins in the past.
It's clear to me that now this is Messi's team and with the right signings(a world class CB and maybe a striker), Messi will lead it to continued success in both La Liga and in the Champions League.