I would agree that neither manager deserve credit for developing him as a centre half and personally was not suggesting they did, just pointing out that it was Mancini who was playing him there at City.Exactly he was a top player capable of playing a number of positions, but neither Hughes or Mancini deserve any credit for developing him into a centre half!
A personal view is that both managers deserve some credit for Kompany though, Hughes for signing a high quality and versatile player at a reasonable price and Mancini for establishing him as the backbone of defense and club captain.