I think that this little addition to a Battle Group would make things very interesting for attacking planes.
Now this:
http://www.ibiblio.org/hyperwar/USN/ships/CL/CL-51_Atlanta.html CL-51 USS Atlanta
Atlanta class Anti-aircraft Cruiser:
Displacement: 8,200 tons
Length: 541'6"
Beam: 53'2"
Draft: 27'
Speed: 32 knots
.
Armament: 16 5"/38DP, 3 X 2 40mm, 1 x 4 40 mm, 15 x 20mm 2 depth charge tracks, 2x4 21" torpedo tubes, 3 SC-1 aircraft
Complement: 820
Geared turbine engines, twin screws, 75,000 shaft hp
Built at Federal, Kearny, and commissioned 24 December 1941
would be a gunners dream and an attackers nightmare personified and would seriously upgrade the longevity of a Battle Group and require considerable forethought and planning before one would want to launch an attack against the battle group.
Attack Co ordination on the enemy airwings part would definitely be a must should this be added to the Battle Groups Heavy Cruiser, Carrier and Destroyer screen.
This would also better reflect the makeup of a Battle Group as seen in WWII