If no one knows about you, you are a 2*. So a bet on the accuracy of the star system is really a bet that college coaches know and can or will find (and offer) most or all of the good prospects.

Therefore, if you are a 4*, you are certainly more likely to be good than a 2*, simply because a 4* means a lot of people have identified you and want to play for them, which suggests you are going to be better on average than the default. Being good is the only reason why you would ever wind up as a 4* in the first place.

But you can be a 2* for a lot of reasons. It could be because 1) lots of people saw you and didn't want you; 2) nobody really saw you; 3) people saw you but for reasons unrelated to your potential decided not to offer (could be you weren't as polished and needed more work, grades, other available prospects, etc.); 4) you played out of position in HS and your athleticism wasn't SO obvious that people wanted you as an ATH or other position; 5) your talents are harder to evaluate (hard work/grit/smarts); 6) you were really young in HS and didn't physically fill out until a bit later; or 7) literally any other reason.

SOME of these reasons might mean something about you as a prospect, but as long as 2* is the default, then of course 4* will be more likely to pan out. BTW, if a school develops an evaluation system that really works but isn't shared by very many other schools, it is very possible that that SCHOOL's hit rate on 2* would be better than the overall hit rate on 4*.

The only reason not to think that is if you believe CFB coaches (and especially P5 coaches, as those offers seem to influence ratings the most) don't miss many kids and aren't lazy in trying to fill out their classes. I tend to think there is laziness, but it makes sense, because it is a question of scholarship limits and options. The better you are as a school, the less you need to be good at identifying under-recruited talent, and the less valuable it is to you to do so.

Highly rated players want to play for you, and fans tend to hang their hats on recruiting rankings, so why would you spend any time searching for diamonds in the rough? In addition, the upside is limited, because if Alabama offers a kid, they are immediately no longer under the radar anyway-- other schools will take a look and likely offer. So to some extent the star system is designed in such a way that it will miss kids. It just will.