Its both, every body benefits from the system of tiki-taka, and the system that barcelona has is benefited by Messi many times for the better as well.. He gives that verticality, provides that change of rythim and the ability to take on a lot of players with confidence and score goals, things that he adds personally to Barcelona because the posesion system and the biotype of the little catalans may be the 'best for creating chances, but might lack goals, or sometimes an indiidual flare that Pedro added to Spain in the World Cup and European Finals for example. He is benefited because he has the talent, if you look at his numbers this year with Argentina, he had more goals than matches in oficial matches and Argentina is soaring 1st looking strong in the lead of the South American qualifiers with Messi as their main man with the goals, the generation of game, and assists.
The little man, like rome pronounced him, has silenced the myths one by one. He now can even score them as free-kicks, as he did in both clasicos? Is that also thanks to Xavi and Iniesta

? Its 88 goals, and another extraterrestrial player is Ronaldo, yet he could only score 62, and tecnically "madrid was a better team the last season", since they won the league. I give him the credit he deserves, his numbers are ridicoulous, he is dominant in every match, if he doesn't score a hattrick in 2 weeks we are all wondering why he's undergoing "the crisis", he is clutch, he doesn't get injured, he's 25, he's amazing, in my opinion Pele is a bloody joke, Maradona is the best ever, and the rest like Best, Platini, Beckenbauer, Zidane are on a lower Pedlestall, Messi has more talent and is more of a beast, than any of the players I named, apart from Maradona, which I can still argue Messi hasn't surpassed yet.
If you haven't seen any of those numbers broken in your life time, and he has broken all the records he has at so young age, you haven't seen any retiring player do it, its because he's something diffent, and I mean it in a way that he probably will be the best ever, top 3 no doubt already.
Edit: About Argentina Romez, i've checked them out in this Sabella era, at first it was pure individual dependency, the Agueros, the Di Marias, Lavezzi, Messi and Higuian moving around and winning by a smaller margin because it would be short sparks of individual brilliance that would win them the game, but 7-8 months back to now, Sabella seems to have found the right balance, a solid defense that hasn't received many goals, a balanced midfield that can break down attacks and feed the ball foward, and a blessed foward that has bagged quite a few goals and won quite a few matches by 3-4 goal differences like Uruguay, who took it straight up the you know what

I think they definetly are a solid competitive strong team now. Argentina dominates their rivals in every match now (in South America), and all the lines seem strong, theres no trouble in the defense, or in the midfield like there was, and therefor the attack is much sharper, furthermore they seem to be a unity defend and attack as whole, its not like 11 players scaterred around, they seem to move together and be one team, finally, and what Sabella did is play like Argentina has always traditionally played is working well .
a few images that say more than a thousand words:
