For a male northern (or any Largemouth strain for that matter) to be so large is definitely extraordinary. Actually, those numbers are probably similar to the odds of being struck by lightning. Seriously. For a male to be so big, lots of factors come into play. Genetics--absolutely. Environmental conditions near perfect, plus all that fish needs to eat. Not only all it needs to eat, but some serious nutrition as well. I'd bet those fish have been genetically selected and nurtured at that hatchery for a long, long time. They probably exchange broodfish as young fish grow into their size range criteria, but males so large are rare.

Regarding the Murvaul story, that lake did have something special going on. It was the first (and only) lake I know of it Texas where northern strain bass grew into double-digits. That happened under TPWD famed biologist Charles Inman's watch. That was before Florida bass started their influence in Texas public waters.

Teach a man to grow fish...
He can teach to catch fish...