You forgot to mention another factor that contributes to program strength: talent evaluation during the recruiting process. By all appearances, Clemson has done a fantastic job in that respect, finding diamonds in the rough, i.e., three star guys who should have been four or five star guys.
One other thing . . . Clemson also appears to be “good” at cheating via the use of performance enhancing substances.
So, recruiting rankings are a useful tool, but that does not mean that high school rankings = college talent. The rankings are a good predictor of talent in the aggregate - five stars will hit at a higher rate than four stars will hit at a higher rate than three stars - but on a micro level, there are hundreds of exceptions.