SAN JOSE, Calif. — Seeing goalie Alex Stalock start for the Sharks at SAP Center seemed preposterous only a few months ago. It was equally unthinkable as of last week. But roughly 14 months after he was diagnosed with a heart condition that threatened to derail his professional career, and just a few days after he was acquired by the Sharks in a minor trade, Stalock got the nod for San Jose on Saturday against the Nashville Predators. But what could have been a feel-good night turned into one of the uglier games of the season, as the Predators flattened the Sharks, 8-0, before a mostly frustra…