I've thrown together some quick numbers based on the 247 recruiting rankings from 2015-2018. Here's the top 15 or so teams based on the average rankings of the 4 years.
Alabama
Ohio State
Georgia
USC
Florida State
LSU
Auburn
Clemson
Texas
Notre Dame
Oklahoma
Penn State
Tennessee
Florida
Texas A&M
What's notable here to me is that USC, FSU, LSU, Auburn and Tennessee are significantly underperforming their recruiting rankings. Even more impressive is that Clemson and Oklahoma are significantly overperforming their recruiting rankings.
Using the CFP final rankings as a measure, other teams that have overperformed (by virtue of not being in the Top 15 recruiting list above) are:
Michigan
UCF
Washington
Washington State
Kentucky
I think the worth of the rankings of recruiting classes is a mixed bag. Clearly, Bama has the best classes up to the past year, and their results on the field match. Clemson has had class rankings of 9, 11, 16 and 7, but they've contended in the past 3-4 years. And what about UCF, who has done amazing things the past 2 years with recruiting classes that don't even hit the radar.
It seems that having a Top 10 class every year is important. But not as important as having the right coaching staff.