Do you think Messi has been working on his free kicks, so he won't ever repeat the same mistake as in the world cup final? In the final he shanked it from a very similar position, where he scored against Espanyol.
Messi has been working on his freekicks ever since he started to take them for Barcelona in 2009 IIRC
the problem is he's not very gifted as a FK taker, i'd say his accuracy can be considered 7/10 but more often than not you'll see the keeper saving his shots because there wasn't enough power behind them even when they were well placed
also although you can't really use luck as factor to measure a fk taker's quality, messi has been consistently hitting the bar through all these years, so those who don't watch him play regularly will think he's getting better when in fact he's about the same as always but slightly more fortunate
The world cup final shot was waaaaaaaaaaaay longer dude