Well, it can be very hard, but that's why they have things like Elite 11 camps for QBs, like AAU ball in basketball, etc. It's why big schools will sponsor their own football and basketball camps, why former pros will set up camps (and invite recruiters), etc.
But it's also why there's groupthink in recruiting. I.e. if a recruit is getting attention from Bama and OSU but they're rated as a 3*, sometimes they'll get a ratings bump because the ratings folks suddenly think they MUST have missed something.
It's why basketball players who (for injury or other reasons) miss a summer of AAU ball often fly under the radar recruiting-wise because they weren't "seen". It's also why some players get huge boosts from their AAU success but then fall flat in real college basketball, because the style of play in AAU is all about scoring and not so much about disciplined team basketball. Heck, it's one of the reasons that Purdue has beaten IU in basketball for going on 5 years straight. IU often gets those AAU stars but hasn't excelled at putting together a basketball team, whereas Painter is extremely good at identifying high-BBIQ players who may not have the same physical gifts and teaching them how to work well together.
Recruiters are right more often than they're wrong, but it's an inexact science and always will be. Heck, the NFL draft gets it right more than it gets it wrong, but it's an equally inexact science.
I mean, at a certain point, they're all kids, and that's just kinda the long and short of it.
You can gather kids together and have them compete. You can see the way the move. You can have the best play the best in practice or even game situations, and learn what you can. But every kid is gonna have drawbacks and every one is gonna be a gamble.
Some let college get to them. Some get overwhelmed. Some bought their own hype and get beat out by kids who didn't. It's an ever-evolving tapestry.
I always think about the case of Marques Colston. Coming out of college, he was a tall, thick receiver with modest speed who played at a small school and wasn’t great. In some sense, one might argue that the NFL should’ve seen whatever it was that made him a future pretty good player.
But he’s said that part of why he got better was that he was so pissed off at being a seventh rounder, he threw himself into the work. And that combined with his gifts, somewhat modest ones for the NFL, to power and uber-productive career. (He also had Drew Brees)
You mentioned the groupthink part, which I sort of agree with and sort of don’t. On the one hand, I think there are all sorts of quirks with the rankings, some that obscure the truth. On the other, I think leveraging the best expertise out there is also pretty helpful.
Because I’m thinking about stories, there was a kid the local college landed a few years back. Big DT, tall, highly athletic. Had a good number of offers, with one current title contender very hard after him. Even then, everyone knew he was soft. But there’s only so many kids that size who move like that, and a staff figured, get him into the program, get him away from mama’s coddling, and we could have a player. (They don’t. He’s still soft, but it’s worth the hassle to potentially have a kid with that physical ceiling if you only have a few)
Sorry to go one, but I think the ins and outs are fascinating. Had a few other random stories that fascinate me that were cut for time.