Some pictures have emerged showing the Moskva under tow shortly before she sank, and several of the boat-touchers I'm in loose contact with have produced some analysis. The Sandbox missiles did not explode, but the imagry availabe shows a fire dangerously close to the aftmost pair on that side. Combined with the signs of heavy smoke residue around all visible portholes, the supposition is that the captain issued an Abandon Ship order fairly early on to preserve the crewmen (information now available suggest that as many as two-thirds of the crew survived) instead of trying to fight the fires, probably due to the risk of a chain detonation of the massive missile battery.
This was compounded by the location of the hits, at leas one of whivh appears (the image detail is not great) to be in the vicinity of the ship's engine room and central damage control. If the latter was put out of commission, that would cripple any effort to fight the fires just as happened to HMS Sheffield during the Falklamds Islands War. This is not a particularly lucky or unlikely hit - the Slava-class ships placed the damage control according to older design doctrine, very close to the areas of the ship that are most critical in combat and centrally located for minimum delay anywhere on board, Unfortunately, this places it right in the centroid of the radar return from the broadside, and anti-ship missiles are going to aim for the strongest part of the return.