2013 has been nowhere near as competitive as 2012, so the cross-comparison is virtually useless. Nevertheless, although Vettel is now the bookies favorite, absolutely nothing is decided yet. Alonso is only 36 points behind, one DNF for Seb, and Fernando has him right where he wants him.
In my opinion, why Vettel is certainly a great driver, in 2012 he was mostly reliant on superior machinery to beat Alonso. Fernando had a 40 point lead when the European races ended. Vettel won four consecutive races in Asia, but the Ferrari never looked capable of beating the Red Bull at any point after Monza.
However, even in this era, designing a faster car than Red Bull on raw pace is entirely possible, McLaren did it last year, and Brawn did it in 2009. The challenging part is to put all the pieces in the puzzle together. Brawn did it perfectly, McLaren failed miserably.
Ferrari have been on the back foot against Red Bull their Windtunnel has been messed up for so long. It has been less than a year since they finally came to grips and have some sort correlation between the parts they design and their performance on the track.
Red Bull on the other hand, has a Windtunnel with five years of correlated data. That is a huge advantage in this era of no testing. Had testing not been banned, and Ferrari could test as much around Fiorano as they wish, they would have none of the problems with the car.
If testing was allowed, I have a feeling Ferrari’s shortcoming would be close to none, and they would probably surpass Red Bull in the development race. As their work will not depend on how good their windtunnel is since the parts would be validated on the test track on a day-to-day basis.