What all of these charts show is pretty clear: The rating services are intentionally "over-ranking" the players that Illinois will eventually sign, in a concerted effort to keep us from our rightful place among the Blue Bloods.
I'm pretty sure this was posted in jest, but it raises an important point IMO. While we can use the recruiting ratings from a service like 247 or even a broader aggregation of evaluations like RSCI as a proxy for any given team's talent, it's still only a proxy based on highly imperfect qualitative information, and as such is difficult to use.
Consider the success rate for, say, NBA scouts in identifying talent. They have the advantage of looking at players who are more mature and who have typically logged significant game time in a much more level and predictable environment than those scouting high school juniors, and their evaluations still miss at a pretty high rate. The probabilities that kids in the top 20 or 30 of the RSCI will be productive in college are pretty strong, but that's a fraction of the 1000-odd kids who sign with NCAA teams each year. Evaluation becomes quite a bit more ragged after that, and gets there in a hurry.
This means a couple of things to me. First, I don't think that it's particularly accurate to assume the talent level of a team is directly and most cleanly related to how kids were ranked coming out of high school and that any failure to live up to the rankings is a result of what came after. I'm more inclined to say that we know more about a player's raw talent level if we consider what they produce at the college level than if we don't. That doesn't mean that player development doesn't matter, among other things, but it seems odd to exclude data points that are frankly quite a bit better than what we have at the time a player signs from the analysis.
The second thing is that if you acknowledge just how hard it is to evaluate the talent level of high school kids, the argument that ratings are biased towards or against certain groups of teams starts to hold some water. And it's possible that it's not a coincidence that IU and Illinois are the two teams showing the biggest underperformance in the league. If you're a long-term national observer, your opinion of those two programs is probably a good deal higher than those who suffer through watching, say, Illinois day in and day out. (To say nothing of the opinions of kids who have only been watching college basketball for five or ten years.)
I don't think that player ranking data really allows for that hypothesis to be proven with any confidence, so that's just conjecture just like everything else is when we talk about recruiting. My personal opinion is that Illinois has, in fact, underperformed its talent level over the past decade, but also that the incoming talent level was not as good as indicated by the ranking services. I apologize because that's not a particularly interesting observation, but I have a tough time believing that we've had first-division B1G talent all along based on what we've actually seen happen on the court.