Some thoughts on rankings:
1) While there will always be variation on some players between ranking services, those services have gotten a lot better over the years. So while there may be some cases where a player is ranked 70 in one and 150 in another, it is hardly the norm and most of those large variations dissipate as the final seasons progress.
2) There is also the notion that the "person doing the rankings" has not seen recruit(s) play. In reality, most of the ranking services are now big conglomerates with many analysts in pretty much all states working for them, including some of the same analysts that Illini fans get their recruiting information from. Analysts working for those services get to watch a tremendous amount of players, individually and collectively. Many more than coaches.
3) Another fan perception is that coaches are better at uncovering talent nationally by watching more players/games than the analysts and recruiting services. This is not true either. Coaches and assistants see very few players/games compared to the analysts. For the simple reason that their schedule/responsibilities do not allow it. Most often than not, when coaches/assistants go to games, it is for players they already recruit, not uncovering talent. I know for a fact that most coaches do depend on ranking services and some of the analysts who work for those services for uncovering talent, recommendations, evaluations, etc. Almost all coaches have open communications with many analysts for uncovering and targeting talent.