I can't read the article - behind a paywall.
I looked at the average ranking the last 5 years starting back in 2018 (before both our coaches started). Per Rivals, UNC's average ranking was about 25. The last couple years its averaged about 14, which is a net gain of 11. Georgia Tech averaged about 50 and went to about 20 for a net gain of 30. 247 says their average was 28 compared to Rivals' 25 and has the same average of 50 as Rivals does. So 247 has UNC gaining about 14 spots, not just 11. But still a fraction of ours.
If you look at roster composite rating by 247, UNC is currently at 22 and we are at 34. In 2018 they were 29 and we were 50. So they improved 7 spots under that measure and we improved 16. To me this measure is this broadest measure which captures the best picture of recruiting, because you get credit or blame for transfers in and out over a full roster period.
Again, I don't know what types of measures they're using, but under any scenario I would use, Mack Brown has improved their recruiting, but not nearly anywhere near the number of spots we have.