wich is why they wouldn't, as I stated, be very efective against dive bombers. Torpedo Bombers during an attack run are another thing. If the DD are providing a close AA screen, the attackers will have to aproach them at low altitude, in a fairly predicatble course, at a predictable speed. That's ideal for AA work.
The DD also know that the target for the torpedos is the BB they are screening, making evasive action less necessary. It the TB target the DD, they will ahve to manouvre hard and loose AA efetiveness, but in that case, the BB are not targeted.
Reality will counter this, as effective AA fire is rarely deployed much later in the war, when no friendly CAP fighters kill the majority for you first. Unopposed Torpedobombers, facing only AA fire (and in the scenario only heavy, relatively slow fireing AA guns, appart from a very few mg's) not controlled by directors, will get through, as the gunners will have to fire manually and on their own innitiative, resulting in a very erratic and uncontrolled barrage, making things easier for the attacker than for the defender. As the escorting DD's themseves were so porly equipped, the AA fire provided by them is neglectable, especially due to their lack of coordination of individual gunners.
So the Kates will simply fly past the blazing DD's (and cruisers), without bothering much about them and concentrate on their objectives, simmilar to what happened with Force Z, where the DD's too formed a ring (although with three vessels a very limmited one) with no results. The only four bombers killed were victims of the multiple 2 pdr's of the capital ships, a sort of weapon the USN completely lacked at the time (the 28mm Quads were too few in numbers and too fragile and troublesome). Heavy AA guns scored no kills, but those of HMS Prince of Wales did do serious damage to three of the high level bombers. HMS Prince of Wales had at the time state of the art firecontrol and airsearch and air target radar sets.
So the point is that a fleet at sea, being attacked by torpedo aircraft and having no CAP of its own, is a doomed one, as AA fire alone cannot prevent it from being attacked. The fleet might not be destroyed completely, but is finnished as an effective fighting unit, since it cannot perform its orders on her own, being at the mercy of the opposing force.
An OTL simmilar sort of action was in the Battle of Leyte, where the US Carriergroups tackled Kurita's Center Group, which at the time had five BB's, eight CA's, three CL's and some 19 DD's. Constant attacks of carrier based aircraft sank Musashi and also hit other ships, for only a few losses, while completely ignoring the dense AA fire of the fleet, which at the time was heavier than in December 1941 on the US Pacific Fleet. Torpedoplanes scored nineteen direct hits on Musashi, indicating that attacking a moving fleet with a large number of other warships as escorts was not save against attacking aircraft and could be destroyed. (Had the USN Pilots not been concentrating on just the biggest ship in sight, they might have had an even better result, hitting other ships more often as well. Yamato, Nagato and Haruna were hit by bombs only in the same phase of the battle.) By the way, the USN attack group consisted primarily of divebombers and TBM's with bombs, while only part of the TBM force had torpedoes, just as with the Pearl Harbor strikegroup.