I will say this again, as it seems that I must not have made it clear in the post both of you quoted, or in a post I made following that one. I am relaying information that JB gave in an interview. Not direct quotes, but the meaning was clear. JB clearly felt that it is very difficult to integrate grad transfers into the team in the short space of time that the situation allows. It is highly likely that this difficulty played a significant part in the team not equaling up to the sum of its parts for a large portion of last year. JB clearly views grad transfers as a risk that he feels are not generally worth taking, unless it is a very special circumstance.
So, you may not like or agree with this assessment, but that is JB's view, and obviously, his view counts way more than any of ours do. It is 100% certain that he knows much more about the issues in the team last year than any of us, so it is also certain that he has a much better idea of how hard it is to get grad transfers to learn & embrace the system, then to reach their maximum capabilities with the system.
My only speculation within the post, was on my viewpoint of Thorpe. I feel fairly confident that JB does not see Thorpe as a "very special circumstance". Feel free to disagree with my viewpoint on Thorpe, but he is not "very special circumstance" worthy, IMO.
As for the comment on the zone, You may feel that it is easy to learn to play it the way JB wants it played, but there is ample evidence that supports that it is a rare player who fully masters its nuances in one year, much less one summer. Even some of the better defenders SU has had, took several years to be effective in the system.