You've basically made my point for me here.His best horse to date Cracksman, his dam never raced further than 10f but he's a proven 12f horse. There is no rhyme or reason.
If Cracksman's dam is by Pivotal and Frankel is from the Sadlers Wells line it is logical to assume the reason he needs a trip is because there is so much stamina in his sires pedigree.
. As you say though, they are finished at 3 or 4. It's all about the money money money