Then if both players have equal concept of positioning and use of cover, that makes OKW stronger.
Not necessarily. The relative effectiveness of factions changes with skill level.
If both players have poor positioning and use of cover then OKW is better than Ostheer because blobbing with Ostheer is a fast track to defeat. If both players are highly competent Ostheer appears to overtake OKW in effectiveness: there's a clear preference for Ostheer over OKW at top levels.