Is it any wonder that they can't compete against teams with similar talent levels? Ian Book was a 3*, and it wasn't by mistake lol, the recruiting services may have been a little too generous with that 3rd star (kidding). Look at other teams in competition for the CFP:
Bama- Tua Tagavailoa (32nd Overall, 5*)
Clemson- Trevor Lawrence (1st, 5* .9999 rating)
Ohio State- Justin Fields (2nd, 5* .9998 rating)
LSU- Joe Burrow (288th, 4*)
It doesn't take a ridiculously high rated player to get the job done, but it definitely doesn't hurt. Guys like Lamar Jackson, Sam Darnold, and Justin Herbert were all lower rated guys and are good/great QBs, the fact that ND hasn't really had a guy that has either A) Lived up to the hype or B) Greatly outplayed his recruiting ranking, leads me to believe that it's on the coaches. I mean, outside of DeShone Kizer it's been a dumpster fire for the most part. I guess if you wanna look at it from a glass half full perspective, BK has still had good success in spite of the bad QB play. Hopefully Jurkovic, Pyne, or Buchner is the answer, idk.