I looked at HS numbers too. Sure, the defenses may not be great, but at the same time the WRs might not be great either and will drop catchable balls. Over a multiple year time period, the overall average can give you a sense about a guy's accuracy. Funny thing when going though the list- 3/4 of the QBs had accuracy in the 57-59% range. That, IMO, means they are just Rosiers at the JUCO level. At a higher level the accuracy would drop big time. 61% JUCO like the dude you mentioned would be 57% D1 (at best) which isn't good enough to beat teams like Clemson.
The guys above 65% actually have some passing skill- if a guy has 68% accuracy at the JUCO level, I'd guess he'd be a 62% passer at the D1 level without any additional coaching. That would still be more accurate than anyone on the roster. In any case, Miami might go into next year with 1 QB on the roster. Take one of those Buffalo QBs and one of these guys. I see no downside to that plan. We need 2 qbs. If that scares Williams off, then good riddance.
Messiah DeWeaver, JUCO kid at East Mississippi CC, 6'5" 230 lbs, 68% completion (JUCO stats)
Tylan Morton, Hinds CC (from GA though so Rick connection) 6'4", 200 lbs, 66.7% completion (HS stats), set Georgia single season record for passing in 2016 (4741 yards). Academics seems to be his issue, which is why he didn't end up at a major D1 program. They play really good football in Georgia, so I'd see if Morton could qualify as I like his potential the most.