Do you think a player rated an 84 is being brought into a QB room, all of whom have 3 years or more of eligibility, because the staff thinks he's going to start?
Realistically the staff knows they can't sell anything to a high school QB who's talented. They aren't coming here for Frost. So they recruited this kid. He's likely going to redshirt and he's going to get his chance in a few years. What they're after is depth, knowing that they're going to lose a few members of the QB room to the portal this fall.
I mean, you're going to believe what you want. Generally speaking, higher-rated recruits tend to work out better. But that's far from a lock. A bunch of NFL QBs were three-star recruits including Josh Allen, Lamar Jackson, Baker Mayfield, Nick Foles, Patrick Mahomes, Dak Prescott, Daniel Jones, Aaron Rogers, Kirk Cousins, Matt Ryan, Russell Wilson and Jimmy Garoppolo was a two-star. That's a third of the league and six of the last eight NFL MVPs.
It's an inexact science, especially for QBs.