Great coaches can be terrible recruiters and great recruiters terrible coaches. Furthermore, a new coaching staff taking over for a successful staff that has moved on gets momentum from the previous staff that helps them bring good players in.
I flat out think your "two-star recruit from NY and NE vs. from FL and Texas" stat is wrong and based on faulty statistical analysis.
Your players don't all "blow up" at the combine, anyway.
2014: 2 participants, both with mediocre ratings at best
2013: 4 participants, all with good but not elite results
2012: 2 participants, both of whom did do very well
2011: 4 participants, with results ranging from mediocre to solid
As for speed coaching, none of the players I saw had elite 40 times except one WR and maybe one CB.