According to 247 Sports Bo was able to bring in 7-9 four star recruits in a 3 year period:
https://247sports.com/Season/2011-Football/CompositeTeamRankings
2013 = 7 four stars Bo
2012 = 8 Bo
2011 = 9 Bo
I think Coach Frost can do that too, hopefully better.
Which means that each of those years there were a lot of 3* or less players. If a coach can identify the talent for his system and develop that talent 3* or 4* won’t seem any different. Also, once he builds this thing you may see more of the higher * players. One last point, as @ShortSideOption has stated many times. NE kids and kids in the 500 mile radius often times won’t be rated as high. Doesn’t mean they aren’t every bit the player another kid in a recruiting hotbed is. If NU can live in that 10-20 range with the occasional outlier either way things will be just fine.