I don't follow recruiting that closely, but based on final rankings, NU has had to have plenty of 4-star recruits and a few 5-stars. The problem is they have either been overrated out of HS, or haven't been developed by previous staffs.
There seems to be a lot of 4/5-star players that dominate in HS because they are superior athletes, but don't put in the work to improve when they get to college and everyone is athletically equal (or better). Even Lebron James and Usain Bolt had to work their a$$es off when they got to the world stage. I know neither of them went to college, but it's the same principle. It's not always about talent, there has to be a drive to improve too. Lamar Jackson when he was at Louisville had a huge arm and great running ability as a freshman, but didn't complete 55% of his passes and only had a 12/8 TD/Int rate. He worked his tail off in the offseason and won the Heisman as a sophomore. His completion percentage didn't increase by a huge amount (56.2%), but his TD/Int rate went to 30/9.
I'm not saying NU has a Lebron/Usain/Lamar kind of player on their roster, but the players they do have need to have the internal drive to improve. It can't always be on the coaches and they can't only rely on their natural talent.