His method didn't change much from his Cincinnati model. While he did pick from a richer talent pool at ND compared to what he was getting at Cincy, there were many prime recruits that he simply didn't bother going after, and it's a good bet that some of them would have come to ND if he would have made an honest effort. Or, he would simply prefer to stick with "his guys" over the more talented player.
He did bring in a fair amount of higher level talent, just not the wealth of riches in upper 4 star and 5 star talent that tOSU, Alabama, etc., would rake in. A lot of those guys did play meaningful minutes.
That plus at Cincy and ND, his greatest strength was taking unheralded 3 star players, and coaching them up to play like 4 or 5 star players, squeezing every last bit out of them. When you look at players such as Julian Love, Nick Martin, Ian Book, Jeremaiah Owusu-Koramoah, etc., and how they played way beyond their projected potential, there's no denying that he was one of the best in the nation at this aspect.
All of the above were good enough to turn his teams into top 10 contenders, but getting over that next hump simply wasn't going to happen under him. The pure talent levels when you compare Alabama, tOSU, and Clemson (during their better years) shows why those guys could regularly contend for the national title, instead of the next highest tier. While there was always a small chance we could hope to pull off an upset (such as in 2020 against a very fine Clemson team), that would require a nearly flawless game on our part, and a big stumbling or misfortune on the other team's part. That's not going to happen on a regular basis if you hope to break even with those teams, much less win two or three of those games in a row.
We got lucky against Clemson in 2020. They were missing several prime defensive players, which allowed us to put on probably the best offensive performance ever in the history of Brian Kelly's tenure here. To put it bluntly, our first stringers had the games of their lives, and were better that day, against many of Clemson's second stringers.
Once those guys returned for the ACC championship game, we got badly exposed.