Matt Cain's promising return from a stint on the disabled list with a strained right hamstring was short-lived. His second start back was even shorter.Washington Nationals' Jason Werth runs toward third base after hitting a home run against the San Francisco Giants during the fifth inning of a baseball game, Wednesday, June 11, 2014, in San Francisco.Washington Nationals pitcher Tanner Roark throws to the San Francisco Giants during the first inning of a baseball game, Wednesday, June 11, 2014, in San Francisco.San Francisco Giants pitcher Matt Cain wipes his forehead during the first inning of a baseball game against the Washington Nationals, Wednesday, June 11, 2014, in San Francisco.Washington Nationals' Jason Werth (28) is greeted in the dugout after hitting a home run against the San Francisco Giants' during the fifth inning of a baseball game, Wednesday, June 11, 2014, in San Francisco.