I don't really see these as formal equivalences, just an attempt to see whether high school rankings (his) ended up predicting with some degree of accuracy how (again, in his view) the same players have performed so far at the collegiate level. If nothing else, it indicates how challenging it can be to measure potential in the case of some (many?) players, as well as how many factors (coach, team, attitude, work ethic, etc., and all of them difficult to measure) influence whether or not that potential is realized or exceeded.
Since she's from my team, Satou Sabally's ratings (36 to 2) are the ones that stand out most to me. Did Olson simply miss the boat in the earlier rating (or the later one), since she's from Germany, and Graves see what he didn't? Is it a tribute to how well Oregon develops players? A sign of Sabally's work ethic and willingness to acknowledge areas she needs to improve? A benefit of the attention given to Ionescu or Hebard (who had a rating even lower than Sabally's), or Ionescu's passes? Some combination? And so on. There's lots to talk/think about, with none of it really provable. In short, something irresistible for a lot of fans.