By Stephanie Apstein San Francisco’s Opening Day starter was always good enough. He just had to stop feeling sorry for himself. High above Philadelphia, Logan Webb wondered if he had ever felt so low. Everything had been going so well: He had grown up 100 miles northeast of Oracle Park, then been drafted by the Giants in the fourth round. His journey through the minor leagues had been mostly smooth. He had given up one run in 17 spring training innings and made the team out of camp. But three weeks into 2021, his first big league season, he could not seem to do anything right. He had been demo…