I don't the answer to this, but I do have a theory FWIW. If the severed engine hit the vertical stabilizer over the bay, one would assume that both would fall into the water, right? However, what if the stabilizer had different characteristics than the engine (i.e., weight, inertia, etc.). Wouldn't the much lighter stabilizer have a different track when compared to the engine? Wouldn't it "flutter" somewhat to earth, while the engine would continue toward the direction of flight in an almost ballistic track? If so, this might explain why the two pieces did not fall in the same location, even though they became severed at alomost the same time. Just a theory.
But it's still bothering me that that stabilizer, from what I could see on tv, did not look damaged, in fact looked too perfect to have been hit by an engine.