James, there is a very fine line here which I'm thinking about. In the midst of moving around a boxer has a very spontaneous attack / response system. They won't just attack, rather, they attack when the attacking is good, hopefully for them. In a sense once the blow is thrown I agree with the no-tracking idea, however, the problem occurs just prior to that when the attack is being engaged. If your timing is even slightly off and you move too early your attacker will modify their attack and be engaged in something which many will deem "tracking" and therefore "bad". It's a very fine line but my opinion is that when you deem tracking bad, with the exception of slow practice or weapons where it can be dangerous, you also restrict out the ability to dynamically adjust based on what nage is doing.
I must be missing your point with baseball because athletes constantly adjust their swing based on the pitch. They don't just swing blindly at the pitch as you imply. Yes, for the few thousands of a second that the swing is engaged they are committed but they are adjusting right up to the point of the swing. For instance, how often do you see a batter "check swing" because what he saw caused him to pull back his swing?
Mostly my resistance to the idea of "not tracking" is that I think it limits the adjustment point to such a degree that we get a false sense of our ability when in reality our attacker would have simply adjusted his strike and tagged us because we took too long too move or he sensed our movement. In other words, I think the concept can dumb down the practice even though it's accurate.
I don't think I did this justice. It needs more writing than I'm prepared to give it.