I do not believe there is any staff that signs players who they do not believe they can help.
Being optimistic has nothing to do with it. We are all optimistic, heck, we have been irrelevant for for more than a decade and we just had a coaching change.
I am very optimistic of Ebo, I think he can help and I believe will be in the main rotation. As I said, every player has a chance to become a star, (including Ebo and Matic) You can say that you have addressed the problem then, but not now, as evident of the many examples, some I mentioned in my post. Otherwise, you can say that you have addressed your gaps every single year, by signing lower ranked recruits at the end of the year. We can do that every year.
Rankings do matter as there are higher chances of success correlated with higher rankings, especially at the higher end. The premise that recruiting rankings do not matter holds no water either. This does not mean that lower ranked players do not have a chance of succeeding (or high ranked players of failing), just that the chances of that happening are much lower.
I think we are in agreement in principle but not in detail. Ranking are not every thing or Kentucky would be a shoo in as national champion in 2 out of 4 yrs. I don't know how their evaluation works (for ranking) but assume they have a point system for shooting, ball handling, etc. It doesn't appear to me to put much emphasis on defense. If it did you could not rate Castleton so far over Johnson. The fit of the player to the system and to the mix is as important as the specific ranking within reason (I.e. High 3 to 4). By helping, I mean they believe they have addressed the problem. Although the player may not be there, they think they can develop him to fill the need. We may learn a lot by the match up of Tilmon vs Spicey in 2018-19. It will confirm both evaluation and development.