What really gets me about this cancellation is just how little effort NBC put into marketing the show.
Compare this to St. Denis Medical. There were a flood of ads for weeks for St. Denis before it premiered, making sure everyone knew when it aired, etc. And it got a pretty good Monday night slot (which, again, everyone knew because NBC constantly aired commercials for it).
I basically learned about Stumble by accident from a Hollywood Reporter article, and then when it finally aired, NBC unceremoniously premiered it in November (well after most new network shows begin) and in a Friday death slot. They never gave it much promotion or much of a chance.
I like St. Denis too, this is no shade to that show. It's just hard not to think if NBC had put any effort into promoting Stumble or given it a decent time slot— let alone the effort they put into promoting St. Denis— we'd still have it.