You'd be hard-pressed to find a coach at ND who has had quite the same level of success that Brian Kelly has had when it comes to finding unheralded, three star recruits (often times, not even high three stars) and turning them into high level college players. He always seems to find 2-4 such diamonds in the rough every year, that with some polish, become fine collegiate players.
At the same time though, they do come with the label of "unpolished," and generally need a couple of years of development. I'm fine with that, provided that they aren't needed right away. However, if they're forced to play too early, then that can throw a monkey wrench into the machinery.
The upper echelon teams the likes of Alabama, tOSU, or Clemson, have plenty of high four star or five star guys who are ready to play from the start, and don't need much polish at all. These are the guys who are already making All-American lists by the time they're in their true sophomore years as well as posing a real probability of wrenching away starting positions from established juniors and seniors.
While we do have a couple such players the likes of Kyle Hamilton, and have had players the likes of Jaylon Smith, etc., they're more of the exception to the rule at ND.
As a season wears on, even the best plans for players get altered due to injuries, lost mojo, etc., and teams that have those polished, hungry freshmen and sophomores ready to play, generally don't lose steam.