Looking at top 15 programs in KenPom and recent hires within past 10 years (in one case 11 years) There is no evidence that you need to take coaches from other P5 programs.
Of the 11 coaches
- 7 were from mid majors (May, Otzelberger, Hurley, Kelsey, Byington, Oats, Golden)
- Only 1 coach was stolen from a fellow P5 program (Underwood)
- 1 was an NCAA assistant coach (Lloyd)
- 1 was an NBA assistant coach (Young)
- 1 was an NCAA outcast (Sampson)
(Note at #16-#20 you do get coaches with P5 success in Pitino, Barnes, Hoiberg) - but they all had various issues at the time of hire.
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#1. Michigan - in a downturn, brought in Dusty May from Florida Atlantic who had recently made the final 4.
#2. Iowa St - in a downturn, brought in TJ Otzelberger, who had 2 poor years at UNLV -- right before that had been great at South Dakota St.
#5. Arizona - in a bit of a downtrun, brought in Tommy Lloyd assistant coach from Gonzaga.
#7. UConn - in a mess, brought in Danny Hurley from Rhode Island
#8, Houston - totally irrelevant, brought in Kelvin Sampson, NCAA pariah, who had not coached for 7 years
#9. BYU - middling, brought in Kevin Young assitant coach from the Phoenix Suns.
#10. Louisville, in a mess, brought in Pat Kelsey from College of Charleston
#11. Vanderbilt, middling, brought in Marc Byington from James Madison
#13. Florida middling, brought in Todd Golden from San Francisco
#14. Illinois middling, brought in Brad Underwood who had went 9-9 at Oklahoma St, after success at Steve Austin U.
#15. Alabama middling, brought in Nate Oats from Buffalo
Excluding the following 4 schools from the above.
#1) Duke a blue blood that can operate differently,
#2) Gonzaga, Purdue, Michigan St they have had same head coach forever.