Ahoi, I've noticed that if there are landbased guns in the capture zone, they would gain control of the zone for your team, when there is no ship inside the zone.
That would make it hard for single SS to gain control, and easy for BB to avoid the SS if the guns are on BB-Team.
I think it's a bug and not a feature...
edit: see the pic with all ships out of control zone, but the BB will capture the zone by the land-guns and the SS and DD will loose that battle if they chase the BB