I'm not saying the Big Three won't be All-Star caliber big leaguers someday, but there is something to be said regarding the patience needed for most prospects drafted out of high school like Mayer and Anthony, or one year of college like Campbell.
Players who spend four seasons at D1 schools almost always began pro careers more polished with more high level experience than prep players.
A good example of this is Reds shortstop Matt McLain, the 5th shortstop chosen in the 2021 draft, after high schoolers Mayer, Jordan Lawler, Brady House and Kahlil Watson. McLain gained four years experience at UCLA and is already a solid major leaguer. The others are still learning.
Before Fred Lynn won AL MVP as a rookie in 1975, Red Sox fans barely heard of him -- except for a potent cup of coffee the previous September. All the hype (minus modern multi-media oversaturation, obviously) was on Jim Rice, the longball legend who never lifted a weight.
But Lynn spent four years in a great baseball program at USC, while Rice was drafted out of high school. Rice made the Hall of Fame for his bat, but Lynn was always a better all-around ballplayer.