I know, it’s only one metric. If you could rerate based on collegian performance (like 247 does with transfers) you would get some very different numbers in some cases. Kam Kichens and A Richards would likely be five stars.
I would also not use a straight average by position, would not treat every position group the same, and would not treat freshman the same as seniors.
Think about the first point. Say for simplicity that Francis Mauigoa is rated 99.999 and Joe Jag Jr. is rated 0.5. That's an average of 0.75. That means an offensive line with one Mauigoa and one Jag is rated the same is an offensive line with two 3-stars... but obviously that's not true. Mauigoa will play and the jag will not. Mauigoa will make plays and lift the position group, and the jags will just be jags.
Even worse, you know your numbers are misleading when you could just drop a jag from the team and "raise" the rating of the postion group, on paper. Obviously removing a player doesn't make your group more talented, you haven't added any talent or difference makers by doing that. You've just raised the average but if anything your team is worse because even scout team players perform a role.
That's why if you want a quick and dirty metric, much better than "blue chip ratio" is just to count the number of 5-stars... because the denominator in the blue chip ratio is completely irrelevant.
Anyway, football is a game of difference makers, not averages. Look at Colorado. One elite player can make a whole position group or even a whole team look good, because they're a difference maker.
And finally on the topic of talent, not all positions are created equal. QB for example matters a lot more than long snapper. Miami played like absolute garbage for about half the game against A&M.... except for TVD who played lights out from opening kickoff till the closing bell. TVD single-handedly lifted us until everyone else started to pick it up. One elite player, a difference maker, at a money position can do that. Look at Colorado's QB.
So the problem with just taking a straight average on high school recruiting rankings is that it doesn't account for difference makers or which positions are more important.