Couple things on my mind after reading this.
1. When projecting further development (trying to find a new top), I don\'t think it\'s a garbage theory. Of course there will be outliers and you\'ll miss some, but in general, a horse that gained 7-8 points from 2 to spring 3 is unlikely to make another significant move forward in the short-term.
2. Some of your examples don\'t really dispose my first point. Orb was the fastest horse going in. Nobody should ever toss out the fastest horse throwing in. If they do, they are misusing TG. Orb and IHA simply paired up to win the Derby.
3. The horses that you listed to move forward, AK, MTB, and Barbaro were eligible to move forward. 3-5 points is not a ton of development. There\'s almost always room there for another a move.
4. Only one horse in your example made a double digit move, and it also happened to be the one horse who only had 1 race as a 2yo and that race was early September. To me, Big Brown never really established a true 2yo top and one shouldn\'t be making development judgments based on one race that was ran early in the 2yo season.
In general (and assuming a healthy line), 7-8 points of development from a 2yo Nov-Dec figure is pretty standard based on my experience. Some will get there in April, some will get there later in their 3yo season, but they often will get there if they are healthy. So I don\'t think the development theory is garbage, it\'s just that it\'s often misused and misunderstood.