Velits rode to 12th in the TT-heavy Tour de Suisse in 2009 and was 31st in the Tour, having been amongst the first home behind the break in the Saint-Girons and Tarbes stages, and outsprinting Thor in Colmar.
In the 2009-10 offseason it was noted more than once that HTC top brass had commented on his having amazingly high natural abilities that simply hadn't been nurtured in the less than ideal situation of Milram.
He was 26th to Xorret del Catí, a steep climb, losing a minute and a half on most GC contenders. He was 13th to Pal, losing a further minute to the winner, and that's quite an easy climb. He lost 45 seconds to Rodríguez on Peña Cabarga, which is only 6km long, and of course Antón crashed out and took a bunch of other contenders with him. The 9th to Lagos de Covadonga is the first real shock result to be honest, but then again the likes of Stijn Devolder stayed with the GC guys to Covadonga in 2007. On Cotobello he cracked and lost 90-120 seconds on the main contenders. However, after the rest day he took 2 minutes out of people on the ITT, then gutsed it out on Bola del Mundo when everybody was content to let Mosquera and Nibali fight out the GC.
Yes, his results were pretty shocking, especially that ITT victory. But he's still improving, young, and had moved into a much more professional set-up.
Gilbert lost nearly 3 minutes on Xorret del Catí, and nearly 8 minutes on Pal. That's one short steep climb and one long gradual one. I don't see him as being able to transform the way Velits did because Gilbert's not going to gain those 2 minutes back on everybody in an ITT anywhere. And let's also remember that with Antón crashing out and taking out at least two of Caisse d'Epargne's riders who were capable of being in the top 10 (and with so many riders in the top 10 but no leader they could feasibly have thrown many an attack out there, which could have hurt Velits on a stage where he struggled like the Cotobello one), plus Menchov having a poor time and Fränk Schleck not being fully over an injury, the Vuelta field was actually much stronger than it looked at the end. If those guys hadn't crashed or had been on form, they were further obstacles to Velits' unlikely podium.
In order to make himself into a probably-not-going-to-have-any-success-anyway GC contender, Gilbert would have to sacrifice a lot of what makes him so good right now, so he shouldn't even think about it.