"It's so frustrating," Kennedy said. "It was such a good start. I thought it was going to be a good day."
Kennedy, coming off a start where he allowed four first-inning runs, was sharp early. He retired eight of the first nine batters that he faced. The only baserunner he allowed during that stretch, Bryce Harper, was erased on a double-play ball in the second inning.
But Kennedy struggled in the fifth inning, allowing a triple to Harper at the end of a seven-pitch at-bat where he threw the Nationals' right fielder just about everything to get him out.
Kennedy allowed another hit and had runners on the corners with no outs. He retired the next two batters he faced and it appeared -- armed with a 2-0 lead -- that he would get out of that potentially messy situation.
Only he didn't.
Danny Espinosa, the Nationals' No. 8 hitter, hit a three-run home run to right field. Then in the sixth inning, Kennedy walked the first three hitters he faced and was replaced by reliever Frank Garces. Three of the four runs that inning were charged to Kennedy.
"He just lost his release point and couldn't find the range on any of his pitches. At times that can get to a pitcher. It looked as though his mechanics were off a little bit in the sixth," said Padres manager Bud Black.
Home runs continue to be a problem for the Padres -- allowing them, that is.
The team allowed two on Sunday, the one by Espinosa and later a three-run, opposite-field shot to left field by Harper in the seventh inning. For the season, the Padres have allowed 54 home runs -- 36 by starters, 18 by relievers.
The Padres also have allowed 10 or more runs in six games of their 39 games this season. They only did so five times a year ago.
"The pitching has to get straightened out," Black said. "Of the current 12-man staff, it's variable from guy to guy. We can't get any momentum built on the pitching side. The talent is there. We have to bring it out of them."
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.