ummmmm.... the old blue-tinted glasses I think!
Kompany is still an average center-half who is getting better all the time, but still learning his position. Central defending is a lot about experience and learning to be in the right position, and doing the right thing at the right times. This is why central defenders dont reach their peak until their early 30's... those who rely on pace then go down-hill quite quickly, the true-quality central defenders stick around until their late 30's.
Kompany is still young and still learning... but is not (yet!) in the same league as John Terry (although if Terry ever recovers from recent injurys still remains to be seen!).
Kompany has all the attributes required to get to the very top if he keeps learning and keeps progressing, but he has been found wanting many times this season... usually through a lack of concentration, positioning, game-reading or pace... 3 games this season especially.... Wolves, Everton & Newcastle (although thankfully in the latter Lescott was excellent!)
The common demoninator in the above 3 games... NO NIGEL DE JONG!
At the moment Vinnie (and our defence in general) is being protected by the best defensive midfielder in the Premier League... if not the world!!!!