On Saturday, November 16, 2013 7:49:54 PM UTC-8, wrote:
If I have a bar drop of more than 4 cm, or a reach -- tip of saddle to bar -- of more than 53 cm -- and I mean by just 5 mm -- my power output drops by 20 - 25% for a given perceived effort. (I know power drops as you get lower, but shouldn't it be more gradual?) Is this just due to my ridiculously short torso? (I'm 73.5"/187 cm tall with 36"/92 cm inseam.) Or, could this mean my saddle positioning isn't ideal? (With all the fiddling around I've done, I would think I would have come across the right combination by now.) Or is this just how some people are? The position is comfortable, not complaining about that. Just can't stop wondering if it means something with the fit isn't correct.

It isn't unusual for you to have been originally fitted improperly and for you to get used to riding a bike that is set too small for your body size. When this is the case you will find even slight changes in position that effectively change the position to even smaller to have disproportionate effects on your power output. In the LeMond years it became "normal" to ride bicycles one to two cm smaller than proper because "it makes me more aero." Since then it's done nothing but gotten worse. Especially now that new bikes are sold in sizes rather than cm lengths of the seat tube and top tube.

Though it sounds more to me as if your top tube is too long and the bars too low to begin with.