>> in Cochran’s case I suspect straight up fraud <<
Maybe, but no evidence so far.
On the other hand, the black vote appears almost certainly to have given Cochran his narrow margin of victory.
Solution? Don’t allow blacks to vote in the GOP primary.
(But something tells me there might be a SLIGHT constitutional impairment to that strategy.)
Solution: closed primaries. But I am not certain that this is the best for every election, particularly in statewide races.