Robbie Ray leaves SF Giants’ game vs. Mariners with hamstring injury

When the Giants traded away Alex Cobb and Farhan Zaidi declared their starting rotation the best in baseball, they were betting the five-man group as assembled could carry them the eight weeks from the trade deadline to the last day of the regular season and, they hoped, into October.

It was a risky wager, with a pair of rookies and another coming off major surgery, and the chances of it paying off took another blow Sunday afternoon when Robbie Ray winced and grabbed at his left hamstring...