IMO if Mangala is told to keep it very simple in terms of passing he'd be better than Stones being told to pass with more freedom.
Maybe I'm just a dinosaur but a CB only has to make a few decisions when not being a "destroyer" -
1. Pass back ( in our case to keepers who can use the ball well)
2. Pass it sideways to the other CB or the nearest fullback (who should all be better to make the next move)
3. Pass it forward a few yards to a CM (providing that there's no pressure)
4. Boot it long
5. Kick it out.
IMO the CB should never be ashamed to do the last 2. Just not all the time ala Dunne :-)
Boggles me that Stones is above Mangala. I want Stones to improve and play to learn but as it stands I'd bet one whole euro that Mangala would be the better partner for Kompany.
If we get another CB I hope they can actually defend.