blind faith in Carmack's abilites
It's not blind faith, it's based on experiencing every engine he has ever written. He is always pushing the boudaries and has consistently produced the best engines in the world. Who would have thought that the DOOM3 engine could produce expansive outdoor scenes of such quality - but look at the new Quake Wars game - the environments are awesome. The engine is obviously well-designed enough that it can be easily modified to produce stunning results in an entirely different area.