The explanation is pretty simple and you hit it early in your original post; limited majors. It is obvious where you fall on the CPJ fan scale, but he was very clear about this in an interview he had with Schultz a couple of years ago. His comment was that the academics can be overcome (your 66% offer rate above), but if you don't have a major that the kid wants, he's not coming. There are a lot of good football players who have the grades and character to get in GT, but we don't have the major they want.
By definition, these are the kind of kids we want at GT. Smart, talented players who are highly motivated both in the classroom and on the field. They have an eye on the 40 year plan and what they want, but we don't offer that path or degree. That didn't change for CPJ and it won't change for CGC. It will be a challenge for every coach we have. GT has some 45 majors; uGa, Clemson, Miami, Auburn, uNc, etc. all have north of 200 options.
This stuff isn't going to change and it will matter to every coach. It isn't as simple as changing to a new coach and we will suddenly have kids lining up. While many perceived CPJ negatively wrt recruiting, his players (and their parents) loved him and he has done the same as his predecessors in rankings. A new enthusiasm and a focus on prep for the next level will help, but until we have more degree options we will be limited in who wants to come here regardless of the system we run.