This thread completely ignores the fact that there simply aren't a slew of good head coaches out there—as proven across the college football landscape—nor does it touch on the situation a new coach takes over.
Let's be honest, how good of "coach" is Lincoln Riley at Oklahoma—or was he just the right guy at the right time taking over a program that had been elite for over 15 years before his arrival? What does Riley look like if he's coaching somewhere else? Same to be said for a Ryan Day—who took over a loaded program Urban Meyer left him.
Dabo Swinney doesn't fit into either of your two boxes above—as he didn't have a Clemson connection, outside of being a positions coach and holdover from a failed Tommy Bowden regime. He also was no CEO, having never even held a coordinators position before becoming interim head coach and eventually the main guy. Talk about a "risky hire".
Took Swinney almost a decade to get Clemson to what it is today—with a lot of setbacks along the way; winning the division year one, backsliding to 6-7 year two, winning the conference year three—but getting smoked in the Orange Bowl (77-30 loss to West Virginia). Looking like a contender year five; getting rolled by No. 5 Florida State, 51-14 at home (the Tigers were No. 3). Had unruly Clemson fans had their way, Swinney would've been canned a few times over those first five or six years.
Poaching Brent Venables from Oklahoma was also a game changer for him in 2013—as Venables is proving to be Bud Foster-like in digging a defensive coordinator role and staying put, opposed to making that head coaching leap. Venables did 13 years in Norman, to leave for the same gig at Clemson? That's an anomaly as most guys don't do that. Would've expected him to stay at OU or to take a head coaching gig—but he's become Swinney's defensive staple and Clemson has had little staff turnover—another shocker as the offensive guys have stuck around, too.
Countless intangibles going into what makes a "good coach"—timing, circumstances, getting enough good brakes to not get run out of town, players staying healthy, more recruiting hits than misses, minimal staff turnover, etc.
Fact remains, Manny is a good fit for Miami in the sense that he gets the program and culture, he wants to be here and he appears to be an up-and-comer type that proved his worth revamping the defense. Not a lot of guys are lining up to take the UM gig and most that do would be using it as a stepping stone to go somewhere else.
Based on all that alone, he's a less risky hire than Swinney was at Alabama—and is more in like with Riley at OU, with the exception that Riley inherited a program that had been a well-oiled machine for almost two decades while Diaz was Miami's fifth head coach in 14 seasons and UM football has been a full blown disaster, leaving it in need of a full-blown rebuild.